Journal of civil engineering and architecture 2013 by CLUDs Laboratory 'Community Local Urban Delevopment'

Journal of Civil Engineering and Architecture Volume 7, Number 10, October 2013 (Serial Number 71)

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Journal of Civil Engineering and Architecture Volume 7, Number 10, October 2013 (Serial Number 71)

Contents Housing and Urban Design 1189

Prices of Apartments in Relation to Noise Level in Poland Kinga Szopińska and Małgorzata Krajewska

1196

Historicity: Preservation or Revitalization Planning Tools? Mariana Seara Paixão, António Ricardo da Costa and Jorge Gonçalves

1203

Study on Emphases and Trend of Tianjin Urban Public Safety Planning from the View of Bohai Rim Megalopolis Gong Yuan, Xiao Yu and Lu Li

1209

Improving Conviviality in Public Places: The Case of Naples, Italy Gabriella Esposito de Vita, Carmelina Bevilacqua and Claudia Trillo

1220

Design Drivers for Affordable and Sustainable Housing in Developing Countries John Bruen, Karim Hadjri and Jason von Meding

1229

Investigation of Bed Joint Reinforcement Influence on Mechanical Properties of Masonry under Compression Lukasz Drobiec

1240

Evaluating the Effectiveness of Best Management Practices in Gilgel Watershed—Ethiopia Tamene Adugna Demissie, Fokke Saathoff, Yilma Seleshi and Alemayehu Gebissa

Gibe

Geotechnical Engineering 1253

Performance of a Nonwoven Geotextile Reinforced Wall with Unsaturated Fine Backfill Soil Fernando Henrique Martins Portelinha, Benedito de Souza Bueno and Jorge Gabriel Zornberg

1260

Models and Optimization of Rice Husk Ash-Clay Soil Stabilization Iloeje Amechi Francis and Aniago Venantus

Basin

Geodesy Applications 1267

Gully Erosion Study and Control: A Case Study of Queen Ede Gully in Benin City Jacob O. Ehiorobo and Roland O. Ogirigbo

1279

Analysis of the Antenna’s Setup Errors at the Global Navigation Satellite System Measurements Evangelia Lambrou

1287

Evaluating Land Surface Changes of Makassar City Using DInSAR and Landsat Thematic Mapper Images Ilham Alimuddin, Luhur Bayuaji, Rohaya Langkoke, Josaphat Tetuko Sri Sumantyo and Hiroaki Kuze

Architectural Design and Related Analysis 1295

The Industrial Heritage and the New Architecture: Teaching, Researching, Designing the Place Identity Monica Bruzzone and Roberta Borghi

1301

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica Walter Salazar, Lyndon Brown and Garth Mannette

1323

The Idea of “Architecture Stage”: A Non-material Architecture Theory Yuke Ardhiati

Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1189-1195 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

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PUBLISHING

Prices of Apartments in Relation to Noise Level in Poland Kinga Szopińska and Małgorzata Krajewska Department of Geomatics, Geodesy and Spatial Economy, University of Technology and Life Sciences, Bydgoszcz 85-225, Poland Abstract: Acoustic climate of a given area ought to be a factor of considerable significance in investment processes in an urbanized area, especially in a residential real estate market, due to its extensive influence on the living standards of its inhabitants. In the following article, the authors have given an analysis of the residential market of housing units located in areas of acceptable and excessive noise levels in preselected regions of Poland. With this end in view, an entirely new source of information has been used in the research—an acoustic map which has been defined and applied to produce the outcome of the analysis. It allowed for the recognition of whether or not the noise level influences decisions made by investors existing in a local residential real estate market. Key words: Acoustic climate, noise strategic map, residential real estate.

1. Introduction Noise is defined as any undesirable, disturbing and harmful sounds causing environmental discomfort. Produced by sources of various kinds, it contributes to the creation of acoustic climate of the environment, in other words an assembly of acoustic phenomena in a given area [1]. Noise sensitivity is a subjective term depends upon predispositions of a person as well as sound characteristics. Thus, certain sounds may in the same time cause pleasant sensations or be disturbing depending on a recipient. Acoustic climate existing in a given area should be a major factor taken into consideration in an investment process of an urbanized area due to its significant contribution to inhabitants’ quality of life, especially regarding residential real estate [2]. Residential properties, as goods satisfying basic needs of a man (such as sleeping, eating, relaxation, family life, studying, housework etc.), have been categorized in Poland into: detached houses, semi-detached and terraced houses, tenement houses, Corresponding author: Kinga Szopińska, Ph.D. student, research fields: environment engineering, real estate management and protection of urban areas from noise. E-mail: k.szopinska@utp.edu.pl.

apartments in residential buildings (including commercial and residential premises as well as cooperative member’s ownership right for residential premises) [3]. Residential real estate in Poland is a consumer market (consumers buy for themselves) to the greater extend and only relatively small part of it is an investment market (apartments for rent) [4-6], which would particularly indicate a significant role of environmental factors while making investment decisions. Due to the fact that housing resources mainly consist of multi-family residential buildings—approximately 67% [7] apartment market which is regarded the most developed one, was the subject of the analysis. Assuming that transaction prices of properties reflect their characteristics, an attempt to answer the question whether the acoustic climate of the surroundings of a selected research area of Poland influences the residential real estate market has been made. The second objective of this paper is to present the extensive use of acoustic maps not only to evaluate the noise level but also as a base for comparative analysis. Therefore the spatial analyses were performed with the use of NSM (noise strategic map), the latest (the first acoustic maps in Poland

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Prices of Apartments in Relation to Noise Level in Poland

were created in the years 2005-2006), professional source of information concerning the surrounding space.

2. Acoustic Map Directive 2002/49/EC of the European Parliament and of the Council of 25 June 2002 relating to the assessment and management of environmental is the major legal act regulating the problem of noise protection which aims at unifying procedures related to estimating the level of environment’s exposure to noise within the member states. According to the directive, NSM is an averaged map of noise generated into environment by various groups of sources, which enables holistic evaluation of a level of noise exposure within an urban area, provides the possibility to determine the origins of such phenomena as well as the opportunity to prepare general prognoses of alterations of its levels. It is the responsibility of state members of European Community to restrict the level of noise in the areas where its harmful influence might affect inhabitants and to protect areas of appropriate acoustic climate. Poland, as a member of European Community is obliged to comply with its law regulations, including the above-cited directive. The primary legal act that regulates the noise exposure safety issues in Poland is the Environmental Protection Act. According to Article 112, noise exposure protection means providing the most proper condition of acoustic climate by maintaining the level of noise which does not exceed admissible values defined by LDWN and LN indicators [8]. The permissible environmental noise level depends on the nature of its source as well as a purpose of the affected area. The values oscillate in the range between 40-60 dB (decibel (dB) is a measure of sound pressure level [9]). NSM consists of a descriptive and graphical part. The first one includes characteristics of an area, acoustic predispositions on the basis of planning documentation of a commune, identification and

specification of noise sources as well as diagnosis of endangered areas. The graphical part consists of maps presenting acoustic climate of a study area. They include immission maps, acoustic conflict maps as well as level indicators of inhabitants over normative noise exposure. According to Art. 7 of Directive 2002/49/EC member states were obliged to compile strategic maps reflecting the situation in the preceding year for all their agglomerations including statements of the period of completion: until June 30, 2007—for agglomerations exceeding 250 thousand inhabitants, until June 30, 2012—for all the agglomeration within their territory. In the view of the directive “agglomeration” is defined as a territory with the number of inhabitants over 100 thousand and population density allowing for being recognized as an urban area by a Member State. In Polish Legal System, this notation is supported by Art. 117 of Environmental Protection Law. According to the article, the diagnosis of the condition of acoustic environment is performed within the national environment monitoring program, on the basis of the results of noise measurement tests for agglomerations of above 100 thousand inhabitants. NSMs have been developed for all the major cities of Poland which exceed 250 thousand inhabitants including: Warsaw, Krakow, Szczecin, Wroclaw, Poznan, Olsztyn or Bydgoszcz. Currently SMAs are being developed for local governments of agglomeration of 100 thousand inhabitants [10].

3. Apartment Market Analysis Considering Noise Level In the present article, it has been stated that participants of local real estate market take into account noise level affecting the neighborhood while making investment decisions such as purchasing an apartment. Verification of this notion will be carried out considering a preselected region of Poland, based

Prices of Apartments in Relation to Noise Level in Poland

on a spatial analysis of transaction prices of housing units in relation to an existing noise level defined by NSM. 3.1 Research Area Characteristics The researched market is residential real estate segment of housing units being a subject to real property ownership rights. The research area is located in the city of Bydgoszcz, one of the vastest settlement centers of Poland, located in the northern part of the country. The city is situated on the banks of the Brda River and Bydgoszcz Canal, whose eastern part borders the Vistula River. The research involves several districts: Akademickie-Wschod, Przylesie, Bohaterow and Bajka covering the area of 458 ha (hektar is a unit of measurement of land area) in Fordon, an administrative unit of Bydgoszcz (Fig. 1). The multi-family residential function is predominant in this area which dates back to one period of history—the 80-ies of 20th century. Service-oriented structures of basic functionality provides complimentary function of the area. Road access is provided by the streets listed in Table 1. Noise generated by engine vehicle traffic in the streets creates higher noise zones which significantly affect the surrounding area [11]. The size of the emission, as well as the transgressions, depend on traffic level and in the same time, the following road parameters: type and condition of the surface, number of lanes and their direction, existing traffic lights as well as speed limits for cars and trucks [2]. The period of prices examination included the Table 1 No. 1 2 3 4 5 6 7 8 9 *

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period of 2009-2010 that is the time following the price correction on the apartment market in Poland, the post-crisis times after which market prices stabilization emerged [4, 12, 13]. It allowed for restraining from making corrections on the basis of price level changes caused by time lapse (time trend equal to 1.0).

Fig. 1 Polish map of selected cities from the developed SNM.

Main streets characteristics in a given area. Street name Fordonska al. Prof. S. Kaliskiego Akademicka Jana Brzechwy gen. Władysława Andersa Igrzyskowa Christiana Andersena Wojciecha Korfantego Prejsa Jozefa Twardzickiego

Road category National Local District Local District Local Local Local Local

m—medium, a—alerting, b—bad, o—other.

Road type Main Service Main Service Main Other Other Service Service

Surface condition* a a b m Asphalt of good b condition o m m m Surface type

Speed limit (km/h) 80, 50 50 50 50 50 30 50 50 50

Prices of Apartments in Relation to Noise Level in Poland

1192

78.86 m2) finishing standards, floor level as well as

3.2 Market Analysis in Spatial Context For the previously defined nature and area of the market as well as the period of prices researching, information of 146 residential unit transactions were gathered. Defined average prices of apartments in the buildings in which the transaction occurred. The study included 45 of the buildings, which accounted for 36.6% of all residential buildings in the analyzed area. Average prices were placed between 2,541.30 zł/m2 ÷ 4,110.68 zł/m2 of useable floor area (złoty is the basic unit of currency in Poland). In the subsequent stage, average prices of apartments in the buildings have been grouped according to the following price ranges: (1) those of average prices placed in the range up to 2

noise level generated by engine vehicles. While attempting to find the answer to the question whether noise influences apartment prices, data concerning very similar properties was gathered with the use of ceteris paribus principle (which means unchanged remaining circumstances), and varying only in terms of one feature which is their detailed location, including noise level factor. The technique allows for researching highly complex problems with the sacrifice of some realism [14]. Unfortunately, it was

apparently

impossible

eliminate

every

distinguishing feature of the apartments in the course of the study, especially those individual ones

3,000 zł/m of useable floor area; (2) those of average prices placed in the range from 2

detailed location, which as a property feature, includes

concerning the finishing standards, total floor area or floor level. Therefore, it has been assumed that

3,000 zł/m to 3,500 zł/m of useable floor area; (3) those of average prices placed in the range 2

introducing three price ranges including similar properties, only varying in some individual qualities,

exceeding 3,500 zł/m of useable floor area. The price ranges included apartment transactions of

into the analysis will greatly decrease the influence of

the same general location, same utilities similar

these attributes on the value, thus detailed location

transport accessibility, similar technical condition of

will remain the only distinguishing feature. Such an

buildings and the same management system. They

analysis policy has been acknowledged right, since the

varied in size (total floor area ranged from 30.73 m to

purpose of the research was not the pursuit of the

4,000

Price of range (zł/m2puz)

3,500

3,000

2,500

Fig. 2

Prices of single transactions in relation to noise factor of the neighborhood [15].

Prices of Apartments in Relation to Noise Level in Poland Table 2

Number of transactions in price ranges depending on meeting acoustic standards by resident areas [15].

No. Kind of area 1 2 3

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Number of transactions in price ranges Below 3,000 zł/m2 3,000 ÷ 3,500 zł/m2 Above 3,500 zł/m2 useable floor area useable floor area useable floor area 6 68 72

For the analyzed area Residential areas meeting acoustic standards (level 1 of noise does not exceed 55 dB) Residential areas which do not meet acoustic 5 standards (exceeded levels of noise over 55 dB)

< 3,000 zł/m2puz

3,000 ÷3,500 zł/m2puz

> 3,500 zł/m2puz

Fig. 3 Spatial location of appartment transactions in relation to a map of excess road traffic noise LDWN (Przylesie, Bohaterow, Akademickie-Wschod districts).

< 3,000 zł/m2puz

Fig. 4

3,000 ÷ 3,500 zł/m2puz

> 3,500 zł/m2puz

Spatial location of appartment transactions in relation to a map of excess road traffic noise LDWN (Bajka district).

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Prices of Apartments in Relation to Noise Level in Poland

importance of noise level as a feature but the question whether, being an environmental condition, it influences the decision making process of market participants. The number of transactions in single price range has been presented in Fig. 2 and Table 2 and their spatial orientation, with the division into districts in Figs. 3 and 4. The information originating from the real estate marked was presented in relation to an extract of a strategic acoustic map of the city of Bydgoszcz. In Poland for the multi-family housing properties accepted road traffic noise level must not excess 55 dB [9].

4. Conclusions The analysis allows for drawing the following conclusions: (1) Acoustic map is certainly a helpful in the analysis and credible source of information concerning noise levels. According to European Union Directive 2002/49/EC, it is available in numerous Polish agglomeration or it will appear in a near future; (2) Most of multi-family residential buildings in the area of the study in Poland—the districts of Fordon in the city of Bydgoszcz is located outside the zone of excessive traffic noise levels; (3) Out of 118 market transactions concerning sales of apartments located in buildings of acceptable noise level areas, most of them (60%) originated from the range of the highest price values: > 3,500 zł/m2 of useable floor area and only 1 transaction from the lowest value range below 3,000 zł/m2 of useable floor area. The remaining, approximately 30%, came from the range of 3,000 ÷ 3,500 zł/m2 of total floor area; (4) Out of 28 transactions of apartments situated in buildings of excessive noise level, a majority of them (75%) obtained lower price level of 3,000 ÷ 3,500 zł/m2 of total floor area and 18% of those—the lowest—below 3,000 zł/m2 of total floor area. Only two of them obtained the highest level;

(5) Preliminary research results have shown that real estate market participants take unfavorable acoustic climate of the surrounding area into consideration while purchasing residential properties, which results in lower price of a given apartment; (6) Unfavorable environment interaction such as noise is reflected in lower market prices paid for residential properties located in areas of excessive noise level. The preliminary results can be further validated using statistical methods such as multiple regression analysis [16].

References [1]

J. Kwiecień, K. Szopińska, Implementation of the EU noise directive in process of urban planning in Poland, international archives of the photogrammetry, remote sensing and spatial information sciences, in: 29th Urban Data Management Symposium, London, United Kingdom, May 29-31, 2013. [2] J. Kwiecień, K. Szopińska, M. Sztubecka, Problem of noise protection in urban areas on the example of Bydgoszcz, Ecology and Technology 18 (4) (2010) 205-212. [3] M. Krajewska, Planning conditions and the market value of real estate, in: E. Siemińska (Ed.), Investment on the Real Estate Market, Scientific Publisher of Nicolaus Copernicus University, Toruń, 2011, pp. 63-99. [4] Analysis of the Housing Market, 2011, http://www.rp.pl/temat/230927.html (assessed Sep. 1, 2012). [5] Appraisal Institute, The Appraisal of Real Estate, 11th ed., Chicago, Illinois, 1996. [6] L. Nykiel, The functions and role of the state in the housing market, Journal of the Polish Real Estate Scientific Society 18 (3) (2010) 7-21. [7] M. Rymarzak, Housing Market in Selected EU Countries, Real Estate—Valuation, Profitability and Risk, Papers and Reports of the Faculty of Management of Gdansk University, Sopot, 2000, pp. 167-174. [8] M. Krajewska, K. Szopińska, The acoustic map as a source of information about the real estates, World of Real Estate 76 (2011) 29-33. [9] Z. Engel, Environmental Protection against Vibration and Noise, Polish Scientific Publishers PWN, Poland, 2001. [10] Noise Map of City of Bydgoszcz, Bydgoszcz, 2008, http://mapy.bydgoszcz.pl/bydgoszcz/index.php/en/ (assessed Sep. 1, 2012).

Prices of Apartments in Relation to Noise Level in Poland [11] C. Asensio, J. López, R. Pagán, I. Pavón, M. Ausejo, GPS-based speed collection method for road traffic noise mapping, Transportation Res. Part D: Transport and Environment 14 (5) (2009) 360-366. [12] E. Siemińska, Residential buildings developers functioning in Poland after the crisis, Journal of the Polish Real Estate Scientific Society 18 (3) (2010) 29. [13] E. Siemińska, Banks’ practical experience in shaping credit policies for financing the real estate market, in: E. Siemińska (Ed.), Investment on the Real Estate Market, Scientific Publisher of Nicolaus Copernicus University,

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Toruń, 2011, pp. 32-42. [14] E. Kucharska-Stasiak, Back to the sources—Discussion about the market value, Valuer 67 (2010) 16-22. [15] M. Krajewska, K. Szopińska, The acoustic climate as a factor affecting the market value of real estate of housing, in: 3rd International Seminar on Urban Investments, Cracow, 2011, pp. 447-455. [16] R. Cellmer, Spatial analysis of the effect of noise on the prices and value of residential real estates, Geomatics and Environmental Engineering Selected Full Texts 5 (4) (2011) 13-28.

Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1196-1202 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

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PUBLISHING

Historicity: Preservation or Revitalization Planning Tools? Mariana Seara Paixão, António Ricardo da Costa and Jorge Gonçalves Instituto Superior Técnico, Universidade Técnica de Lisboa, Lisboa 1049-001, Portugal Abstract: The historic centres revitalization addresses the challenges related to the preservation of fundamental heritage values. At a time, when everyone looks with concern to our cities’ future, it is important to reflect on the received heritage, seeking the most appropriate answers to the planning of the historic centres. These fabrics are reference places in the urban space, due to their role of memorial testimony and of generators of cultural and economic dynamics. However, often times, inherited urban fabrics are affected by the limitations of the heritage policies which, for being too general and based on theoretical and abstract frameworks, have difficulty incorporating the characteristics of each area and neglect the formulation of specific criteria and intervention methods. The purpose of this paper is to provide a comparative reading of the levels of urban renewal allowed by the planning tools. This study chooses two historic centers in Portugal: Oporto and Guimarães historic centres (World Heritage Sites since 1996 and 2001, respectively, and were the last to get this classification in Portugal). This reflection is a contribution to peer trends and raise the discussion on the role that the different heritage policies have to the revitalization of the historic centres. Key words: Historical centre, planning tool, urban renewal, heritage, urban planning.

1. Introduction  Cities are concentrating their worries on territory qualifications and the central territories have seen their role reinforced on the social and economical development promotion of themselves. It is urgent to tackle the challenges related to the safeguard of heritage fundamental values along with the need for revitalization of historic centres, giving them new functionalities

and

residential

attractions.

Consequently, it is important that pre-existence management policies are capable of their preservation and at the same time adequate for present and future challenges. Heritage policies dictated by current planning tools represent the conservation strategy adopted by each historic centre. We will be looking to evaluate the different policies adopted for this heritage preservation, especially concerning its adaptability capacity for a sustainable future. Corresponding author: Mariana Seara Paixão, master, research field: urban morphology. E-mail: m.seara.paixao@gmail.com.

2. Historic Centres: Conceptual Evolution and Heritage Policies 2.1 Concept Developed up to 1st World War The urban heritage concept has changed with time in its articulation with the historic centres, in accordance with the social perception of the value of this resource. Urban renovation policies adjusted to its own heritage evolution in accordance with its respective era, social characteristics, culture, economics and policies. In this evolution, we can emphasize three distinctive phases of urban renovation policies: preservation, conservation and heritage [1]. Preservation was the first phase for these policies and focuses on buildings looked upon as monuments, selected by beauty or age criteria. The constructions were preserved by legal protection rules imposed by specialists, whom identified its relevance as cultural goods [2]. 2.2 Concept Developed between World Wars The 20th century modern movement upholds a

Historicity: Preservation or Revitalization Planning Tools?

radical approach for the intervention and resolution of historic centre’s problems. The modern movement supported the destruction and reconstruction according to modern principles, not giving especial importance to the pre-existences, as exemplified by the Voisin Plan (1925) conceived for Paris by Le Corbusier. However, at the same time, radically opposed concepts started to emerge to this approach of looking at the inherited city. We underline the works of Gustavo Giovannoni—for whom the historic city was a monument, because of its topography, landscape character and the set of built typologies. It is after the 1st world war that the intervention in historic centres considerations intensify, because a fast answer became imperative for the rebuilding of the destroyed cities. The Italian Giovannoni gave an important contribution, for this reflection, in formulating the urban heritage concept, considering the historical city as a density of relevant values. We underline the works of Gustavo Guiovanni who developed the minor architecture concept meaning a monument conception viewed not anymore as an isolated spatial piece, but with an essential surrounding for its understanding [3]: one asset that should be preserved through protection laws as it already existed for isolated monuments [4]. 2.3 Concept Developed after the 2nd World War It is only in the sixties, a strong economical recuperation period after the 2nd world war, that renovation methodologies in historical centres were implemented for the first time in Europe, such as the Plan de Sauvegarde et Mise en Valeur do Marais (1969) in Paris, and Bolonha’s Historical Centre Regulating Plan [5]. These places were degraded physically and at a social, cultural and economic level, enabling the change for a second phase of urban conservation policies, the conservation, magnifying the attention aimed at urban sets [2]. At this stage, the goal was to better the physical environment, such as housing, and at the same time, solve the social

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problems of the resident population. Nowadays when everybody anxiously looks with concern to the city’s future, it is important to reflect over the received heritage of the past, in order to search for the most adequate answers for planning and managing of the historic centres in the set of the contemporary city. The international orientations mirror the worries and distinctive attitudes towards the preservation and conservation of historic centres as a resource and legacy for future generations. General heritage safeguard international documents show us a diversity of conceptual evolution that justified the intervention in these places, like as the role of contemporary architecture and urban planning. Five relevant international documents can be identified: (1) Nairobi’s Recommendation (UNESCO, 1976) determines that the historical set and its surrounding are a coherent whole, but identifies new constructions as a threat that could destroy the set’s character (consulted in Ref. [6]); (2) Resolution 813 (Council of Europe, 1983) assumes as a guide rule the need to integrate contemporary constructions in historic sets, in order to give continuity to the architectural tradition and building a future European heritage (consulted in Ref. [5]); (3) Washington’s Charter (ICOMOS, 1987) identifies as a guide rule that the historical sets safeguard should be carried out through social and economical coherent development policies. It supports the preservation of urban forms, of the built and empty spaces relationship, building’s form and function (consulted in Ref. [6]); (4) Burra’s Charter (ICOMOS [7]) for the first time identifies a larger conservation concept, “Conservation means all the processes of looking after a place so as to retain its cultural significance” (Art. 1.4) which “means aesthetic, historic, scientific, social or spiritual value for past, present or future generations.” (Art. 1.2);

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Historicity: Preservation or Revitalization Planning Tools?

(5) Vienna’s Memorandum (UNESCO [8]) identifies as guideline the acceptance of the city’s building process, in which change plays an integrated part. It defends heritage conservation and simultaneously its modernization strengthening its own identity and social cohesion. Hence, contemporary architecture should complement the existing urban historical landscape as a fundamental strategy. Historical centres today are treated by the third phase of urban renovation policies, the heritage, which occurred when they came under a market orientation [1]. The architectural legacy began to be seen as a consumer selected product, and managed by current market demands. The past is molded to answer contemporary needs [9]. It has become an urgent necessity that conservation and urban planning have a symbiotic relationship that leads to harmonious cities development [10]. Historic centres carry a double achievement of being a memorial witness, as well as a generator of cultural, economic and social dynamics, crucial for the cohesion and qualification of the contemporary city. Therefore, historic centres are reference places in the urban space. However, the urban net legacy is many times penalized by the heritage policies limitations that, by being too general and established by theoretical tables, have difficulty in incorporating each intervention area’s singularities. Usually heritage policies do not care for the formulation of criteria and methodologies adjusted and adapted for each case. Planning in historical sites resides nowadays in the dictum between preserving the past, by its intrinsic value, and the transformation necessity, answering to the values of a restless for innovation, inclusion and culture seeking society. As such, if urban areas do not have the ability to change, they will end up stagnating in the set of the urban fabric [11]. “Conservation is a complex process of managing the tensions between continuity and change in the city,

and its main aim is to manage the cultural character and identity of the city” [12].

3. Evaluation of Clearness and Renovation Capacity of Planning Instruments in Emblematic Portuguese Historical Centres When the planning instruments have explicit rules, it minimizes the bureaucracy and maximizes the margin of interest in the projects, thus boosting economies, population flows, services and cultural programs to these historic centers through a clear and objective management of urban renewal. This can result in a gradual and rigorous transformation of the built fabric that leads to the preservation, revitalization and sustainable development of this urban heritage. The following analysis focus on two historic centres in Portugal: Oporto and Guimarães historic centres, which are World Heritage Site since 1996 and 2001, respectively. These two historic centers were the last to get this classification, of the four existing World Heritage historic centers in Portugal. The current planning and management instruments for these historic centres reflect different ways of thinking and intervention on built heritage enabling us to understand the different policies adopted for the conservation and renewal of these world heritage urban places. 3.1 Guimarães Historic Centre 3.1.1 Plan Type and Management Entity In the historic centre of Guimarães the Local Technical Office (GTL (Gabinete Técnico Local)) is the responsible entity for managing the interventions in buildings (Fig. 1). This entity has a threefold objective of maintaining the population, provide better living conditions and preserve/restore the heritage values of authenticity. The GTL advocates a logical maintenance and minimal impact through the use of skilled local labor, materials and traditional techniques.

Historicity: Preservation or Revitalization Planning Tools?

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3.2 Oporto Historic Centre

Fig. 1 Plan with the delimitation of Guimarães historic centre classified as World Heritage (in blue) and its protection zone (in red) [14].

3.1.2 Criteria and Levels of Intervention The Local Technical Office classifies interventions according to two categories: light works and deep works. Light works focus on repairing facades, eaves, window frames, painting elevations or introduction of sanitary facilities. Deep works include interventions in the structure and interior organization. This entity elaborated the Regulation for Intervention in the Urban Center and History of Guimarães (RICUH, 1994), which requires multiple constraints for urban renewal. It constrains exterior characteristics, as facades design, colors and materials, these should be maintained as the originals. In buildings interior the same method is applied, original typology and materials should be also preserved.

3.2.1 Plan Type and Management Entity In Oporto’s historic centre, the built heritage intervention management is run by Porto Vivo—SRU (Urban Rehabilitation Society) [13], whom since 2004 produced Strategic Documents for each block, assuming each of these as an intervention unit (Fig. 2). These strategic documents establish the foreseen and authorized works in each building, safeguarding the minimum sanitarian and habitability conditions. The strategic documents have law enforcement power over the building and has to be followed both by public and private dwellers. The foreseen interventions were produced by the joint work of Porto Vivo—SRU with the Portuguese Institute for Management of Architectural and Archaeological Heritage (IGESPAR—Instituto de Gestão do Património Arquitectónico e Arqueológico). 3.2.2 Criteria and Levels of Intervention Porto Vivo—SRU’s strategy covers an extended range of concerns placed both on the survey and diagnosis of the existing conditions and in the procedures for the intervention management (Table 1). The Porto Vivo—SRU, with a deep knowledge of its intervention area and in order to clarify its intervention criteria in the historic centre buildings, has also established three building intervention categories: light, medium and deep. A light intervention is applied in buildings in a reasonable conservation state and the intervention can not interfere with the daily

Fig. 2 Plan with the delimitation of Porto historic centre classified as World Heritage (in pink) and its protection zone (in yellow) [15].

Historicity: Preservation or Revitalization Planning Tools?

1200 Table 1

Intervention criteria in Oportoâ&#x20AC;&#x2122;s historic centre.

1. Intervention technological aspects

-Understanding and respecting the existing building, the primitive technologies, and if not possible assuring that new technologies are compatible with the old ones. -Maintaining and qualifying elevations, through consolidating operations; 2. Urban Elevations -Repairing and cleaning (reposition of original elements by withdrawing unfitting elements). -In profound or deep interventions, to maintain the elevations, and main building side walls, in order to maintain relationship between external openings and internal spaces; 3. General typological -In deep interventions there are typological reformulation operations, in the scope of plot definition, resolution internal spatial room alteration, horizontal and vertical distribution common areas alteration, with the introduction of lifts, equipments and services demanded by current legislation. Aims to any level of intervention: -Respect as much as possible for buildingâ&#x20AC;&#x2122;s insertion environment; 4. General criteria for technical -General rehabilitation and anomalies correction, focus on structural safety and fire risk; interventions -To abide current demands for new construction whenever possible; -Primitive elements upgrading, with authenticity, safeguarding their compatibility with new intervention elements. (a) Structural safety: -Introducing new structures (concrete, metal or steel) to reinforce the building main structure and creation of new vertical communications; -Traditional timber structures ( ensure fire safety, acoustic insulation and waterproofing in water areas); -To reinforce foundations and seismic resistance. (b) Safety against fire risk: -Risk reduction measures of fire starters and fire spreading. (c) Hygrometric thermal comfort: -(New construction or deep intervention) uphold thermal comfort passive systems , to reduce heating thermal charge, through good insulation and minimize cooling active systems (air conditioning); -(Existing construction rehabilitation or light interventions) reinforce roof thermal insulation, renewal of degraded openingâ&#x20AC;&#x2122;s frames (thermal bridges); 5. Securing of main demands -Insulation reinforcement (roof, opening frames, double glazing, lowering thermal bridges, bettering night ventilation systems). (d) Acoustical comfort: -(New or deep constructions) fulfillment of current demands; -(Existing constructions), sound insulation between storeys (ceilings and/or roofs) and between plots, reinforcement and insulation of opening frames. (e) Healthcare of conveniences and kitchens: -Employment of ventilation, water supply and drainage, necessary equipment and washable, waterproof and resistant finishes. (f) Services and infra-structures: -Application of rainwater drainage, telecommunications, active security and gas systems. (g) Durability and economics: -Pragmatic attitude in solutions choices, as to cost and acceptable durability, through control and critical continuous assistance in all project phases.

Source: Ponte Nova, PBDE, Annexe II.

life of the residents. The medium intervention concerns the repair of timber works and opening frames, reinforcement of some structural elements, as floors, roofs and walls. It also includes the improvement of the commons parts of the buildings and upgrading functional conditions in accordance to current legislation. The deep intervention mainly includes light and medium interventions and it is also about changing the typological organization (number of plots, functions). It implies demolition and reconstruction, it also allows changing materials and

finishes and can imply temporary relocation of the building residents.

4. Conclusions This reflection is a contribution not only to interpret the effects of the different planning tools in the architectural interventions in historic centers, but also to peer results and trends. Thus it raises the discussion about the role that these different policies assume through the planning tools to the urban conservation and renewal, i.e., in the revitalization of the historic

Historicity: Preservation or Revitalization Planning Tools?

centres, which possess strong identity valences. Comparatively, we can see that the planning tools that allow greater urban renewal are the Strategic Documents in Oporto. In this historic centre, the strategy developed by Porto Vivo—SRU is based on the deep knowledge of the buildings, preserving its original design and aesthetic from the exterior, but allowing contemporary interventions that benefit the whole. The strategy followed by Porto Vivo—SRU allows a deeper intervention inside the buildings, with the aim to provide the standard conditions of habitability for contemporary people that want to live in these places without losing comfort. In Guimarães the RICUH, designed by the Local Technical Office, reflects a reduced possibility of intervention with contemporary values in this historic centre. Almost all characteristics must remain as the original features of the buildings, either exterior or interior. In our interpretation, this shows a strategy of perpetuating the past values, believing that contemporary architectural values would reduce the artistic, social, cultural values and the economic development acquired by the place so far. Although in both cases different levels for intervention are set (Oporto—light intervention, medium intervention, deep interventiona and Guimarães—light works and deep works), the planning instruments establish clearly different approaches to deal with the urban renewal of the built heritage. In sum, we can understand that the latest Portuguese planning tools, and the Strategic Documents in Oporto, are the most complete and flexible. They cover, for example, how to intervene on the building’s structural system and they also point out objectively the constraints relating to the factors of facade design, roof and internal typology. This planning approach, through strategic documents, allows a regulated change of the historic centre. On the other hand, the approach developed for Guimarães historic centre defends quite the opposite, it supports the idea of maintenance of the past as it, not adding

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contemporary values. As suggested by the Vienna Memorandum [8] in the management of architectural interventions in the historic centres must exist as a principle the acceptance of change as part of the construction of the city, not only advocating the preservation of heritage, but also and at the same time, the upgrading in order to strengthen the identity and social cohesion. The planning tools of Oporto, and the Strategic Documents, are the ones studied that best embody the idea of preservation and revitalization support by the Vienna Memorandum, which is necessary to keep the historic centres actual and alive in the contemporary city.

References [1]

G.J. Ashworth, From History to Heritage—From Heritage to Identity: In Search of Concepts and Models, Building a New Heritage, Tourism, Culture and Identity in the New Europe, Routledge, London, 1994, pp. 13-30. [2] S. Tiesdel, T. Oc, T. Heath, Revitalizing Historic Urban Quarters, Architectural Press, Oxford, 1996. [3] F. Choay, Consulted Version, The Allegory of Heritage, Edições 70, Lisboa, 2008. (in French) [4] J. Aguiar, Some brief notes on the history of urban renewal, in: The Conference of Challenges and Proposals for an Application for World Heritage, Universidade de Coimbra, Coimbra, 2007. (in Portuguese) [5] A.M. Tung, Preserving the World’s Great Cities, The Destruction and Renewal of the Historic Metropolis, Clarkson Potter, New York, 2001. [6] F. Lopes, M.B. Correia, Architectural and Archaeological Heritage-Charts, International Conventions and Recommendations, Livros Horizonte, Lisboa, 2004. (in Portuguese) [7] ICOMOS, The Burra Charter, Australia, 1999, http:// australia.icomos.org/publications/charters/ (accessed May 24, 2011). [8] UNESCO, Memorandum de Viena aquando da Conferência Internacional “Património Mundial e Arquitectura Contemporânea—Gestão das Paisagens Urbanas Históricas”, 2005, http://whc.unesco.org/archive/ 2005/whc05-15ga-inf7e.doc (accessed May 30, 2011). [9] N. Nasser, Planning for urban heritage places: Reconciling conservation, tourism and sustainable development, Journal of Planning Literature 17 (2003) 467-479. [10] N. Cohen, Urban Planning, Conservation and

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Preservation, McGraw-Hill, New York, 2001. [11] P. Larkham, Conservation and the City, Routledge, London, 1996. [12] W.K. Liu, Managing change: Tensions between urban morphology and everyday life in the heterotopic urban content of Tainan, Ph.D. Thesis, University of Edinburgh, UK, 2011. [13] Porto Vivo—SRU, PBDE (Plano Base do Documento

Estratégico) Ponte Nova, 2006, http://www.portovivosru.pt/ (accessed Apr. 14, 2011). [14] Câmara Municipal de Guimarães, Gabinete Técnico Local, Regulamento de Intervenção no Centro Urbano e Histórico de Guimarães [online], 1994, http://www.cm-guimaraes.pt/ (accessed May17, 2011). [15] IGESPAR Homepage, www.igespar.pt (accessed Apr. 4, 2011).

Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1203-1208 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

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Study on Emphases and Trend of Tianjin Urban Public Safety Planning from the View of Bohai Rim Megalopolis Gong Yuan, Xiao Yu and Lu Li Tianjin Urban Planning and Design Institute, Tianjin 300201, China Abstract: Nowadays urban public safety has been an important subject of study in urban planning study. And planners realized that a safe city is very important for sustainable development. Traditional urban public safety planning begins to perfect the contents and method. And regional research is an important aspect in the improvement of new era urban public safety planning. This paper chooses Tianjin, the important city in Bohai rim area as the example for research. Tianjin urban public safety planning includes not only comprehensive disaster prevention and reduction, effectively preventing and reducing disasters, ensuring the safety of the life and property of the residents, but also sharing resources and facilities from the view of megalopolis, eliminating hidden area troubles, reducing whole environment risks and so on. Key words: Urban public safety planning, Tianjin, Bohai rim megalopolis, emphases.

1. Introduction Nowadays urban public safety has been an important subject of study in urban planning study. And planners realized that a safe city is very important for sustainable development. China government begins to pay more attention to urban public safety system and perfect the contents and method of traditional urban public safety planning. 1.1 Understanding of Urban Public Safety Risk Sources Risk sources that pose threats to urban public safety are classified as natural sources, man-made sources and other sources with natural and artificial factors. The public safety emergencies fall into four types according to the documents issued by China—Master State Plan for Rapid Response to Public Emergencies in 2006 and Emergency Response Law of People’s Republic of China in 2007: Natural disaster: It covers drought and flood, meteorological disaster, earthquake, geological disaster, marine disaster, bio-disaster and forest and Corresponding author: Gong Yuan, chief planner, research field: urban planning. E-mail: gongy20001@163.com.

grassland fire, etc.; Accident disaster: It covers all kinds of safety accidents in industrial and mining enterprises, and trade and business, traffic accidents, public facilities and equipment accidents, environment pollution and ecological destruction, etc.; Public health events: It covers infectious diseases, mass unexplained diseases, food safety and occupational hazards, animal epidemic diseases and other events that will heavily affect people’s health and life; Social security: It mainly covers terrorist attacks, economic safety events and foreign emergencies. Through matrix analysis of affection and relationship between urban public safety risk sources and urban planning, we confirm that all nature disaster, environment pollution and ecological destruction in accident disaster, water safety in public health events and terrorist attacks in social security have the closer relationship with urban planning, and will be our research emphasis [1]. 1.2 New Task of Urban Public Safety Planning It is a new task about urban planning and

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Study on Emphases and Trend of Tianjin Urban Public Safety Planning from the View of Bohai Rim Megalopolis

construction to establish urban public safety system and emergency management system. To establish the public safety system of cities and improve the overall safety of cities, we should take the emergency management ability and the risks from urban construction into accounts at first. Therefore, the research of urban planning would face new challenges as follows [2]: • Firstly, the existing traditional system of disaster prevention and reduction would turn to integrated safety system of urban public; • Secondly, we need to conduct the design and construction of urban planning in terms of the demand to establish sound social warning mechanism, emergency mechanism and social mobilization system, and improve the disposal of emergency and public safety; • Thirdly, enhance the integrated and full management of urban planning. Turn single disaster management to integrated disaster management and crisis management, turn the safety prevention of cities to the full management covering prevention, emergency response and reconstruction, turn the operation of a single system to the overall system;

River Delta and Yangtze Delta, which is constituted by Beijing-Tianjin-Hebei area, Shandong Peninsula and central-southern Liaoning Province (Fig. 1) [3]. As a channel for northern China to conduct its opening up, Bohai Zone is the gateway for opening up to the outside world in the north of China and plays an important role in connecting the south and the north, as well as the east and the west, and also in participating the global economy competition and cooperation, especially in northeast Asia area. Under the support of national strategy and policy, it is necessary and possible to shape up integral and huge world-class urban megalopolis. Bohai rim megalopolis research scope including two municipalities (Beijing and Tianjin) and three provinces (Liaoning, Hebei and Shandong) with land area 522,000 km2 and sea area 95,000 km2. Bohai rim megalopolis has population of 240 million in 2011 which occupy 17.8% of China and GDP of 10.1 trillion RMB in 2010 which occupy 25.3% of China. Now this megalopolis is in its increasing period and it is important to establish a comprehensive region public safety cooperation mechanism as soon as possible [4].

• Fourthly, under the public safety planning process implement the regional coordination and urban-rural integration theory, and expand the perspective and thought in drawing up the public safety plan.

2. Bohai Rim Megalopolis Development and Tianjin Urban Public Safety Trend 2.1 Bohai Rim Megalopolis Development The rapid expansion of urban megalopolis have become an overwhelming space phenomenon in the era of economic globalization and information, and the megalopolises all over the world have gradually become the larger metropolis area and city groups. Urban megalopolis has also become the main form of towns in China. Bohai rim megalopolis is entering the integrated development period of strategy with Pearl

Fig. 1

Bohai rim megalopolis research scope.

Study on Emphases and Trend of Tianjin Urban Public Safety Planning from the View of Bohai Rim Megalopolis

2.2 Tianjin Public Safety Trend from the View of Bohai Rim Megalopolis At present, the overall situation of Tianjin public safety is stable. With an analysis of the disaster sources due to Tianjin’s geography and climate environment, geological factors, ecological factors and the city itself, the potential natural disasters of Tianjin include drought, flood (including storm tide), earthquake and other disasters which derived from the above disasters. Among them, flood (including storm tide) and earthquake belong to emergency disasters. The rescue is difficult and it needs to enhance the prevention of disasters in case of no disasters.

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“Qilihai-Dahuangpu” marsh and the “Tuanbo-Beidagang” marsh. It is also an important part of the security system of ecological safety in Bohai rim megalopolis (Fig. 2); (2) We attempt to establish the ecological compensation mechanism by the Luanhe-Tianjin water diversion project, and take market method of compensation such as the transfer of water rights and paying for the water resources. And we also actively explore the compensation method of technological projects, help to develop pollution-free ecological industries in upper water resources of Hebei by taking advantages of technology and fund, and finally

On the other hand, after 9.11 attacks, terrorist

achieve the balance between development and

attacks which aim to attack metropolises now have

protection. At last, we will explore the safeguard

gradually become the key research of urban public

mechanism for regional public safety;

safety. Bohai rim megalopolis takes the key strategy

(3) We should perfect the monitoring and feedback mechanism of water quality in Haihe River, control the water quality of trans-boundary rivers, and

as the co-built of world-class cities by Beijing and Tianjin and focusing on the development of coastal areas. Tianjin and Beijing would bear responsibilities for various urban functions of world and own ports and coastlines at the same time. It is more likely for Tianjin to face terrorist attacks whether from perspectives

politics,

economy

culture.

Therefore, Tianjin must play a significant role in maintaining national safety and lifeline system. And public safety planning of cities based on the traditional integrated prevention planning of single city,

should

establish

system

from

regional

perspective and guide Tianjin to build a safe city under the new national strategy.

3. Study on Emphases of Tianjin Urban Public Safety Planning from the View of Bohai Rim Megalopolis 3.1 Establishing Ecological System of Regional Integration (1) An ecological pattern of regional integration and pilot projects for ecological compensation have been conducted in Jixian Mountain, the

collaboratively manage the pollution resources in villages and cross-regional watercourse. We should improve the river pollution control by taking Haihe River as the breakthrough point and protect the regional water; (4) We should protect the coastlines of Bohai Gulf, optimize the coastal industry distribution with policy and market control, cut the total amount of emissions in waters and prevent the environment deterioration and ecology unbalance in coastlines to achieve the safe use of sea. 3.2 Improving Regional Carrying Capacity of Water Resources and Environment Water shortage is the main bottlenecks to restrict the development of Tianjin and Bohai areas, and the public safety hazard that Bohai areas would face in the future. Water shortage would be increasingly prominent under the city’s rapid development and the investment of a large number of great and good projects in high level. Therefore, from the perspective of regions, we should focus on the development strategy

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Fig. 2

Study on Emphases and Trend of Tianjin Urban Public Safety Planning from the View of Bohai Rim Megalopolis

Ecological pattern of regional integration.

of Tianjin water resources in urban planning of public safety. We should vigorously promote the desalination and take full account of the relations between development and protection to realize the integrated development and comprehensive utilization of the water resources such as surface water (including transferred water), groundwater, desalinated water and resurgent water. And in the process, we should conduct water-saving at first, focus on urban and rural security of water supply, and take full account of the carrying capacity of water resources and environment: (1) We should make use of the advantages of

seawater desalination in Tianjin, and provide more water resources for surroundings to alleviate the widespread water shortage problems in Bohai areas; (2) Build an industrial chain of “thermoelectricity-desalination-salt manufacturing with concentrated seawater—the extraction and use of chemical resources on seawater”, develop seawater desalination technology, promote a serious of new measures and new technology of seawater desalination in the river estuary, promote the use of clear energy and recyclable energy to achieve energy-saving goals and reduce the impact of desalination on ecological environment;

Study on Emphases and Trend of Tianjin Urban Public Safety Planning from the View of Bohai Rim Megalopolis

(3) Under the development of the non-traditional water resources such as recyclable water and seawater, we would further enhance and perfect the use and management of traditional water resources, and increasingly support the Tianjin water resources by inter-basin water transfer project. 3.3 Improving Regional Sharing and Linkable Traffic and Communications Network In the planning, we establish high level traffic and communications network in the city, from city to city and from region to region and create various methods to realize the space rescue and evacuation in case of emergencies due to different reasons. The road network structure in emergency regions would have direct impact on the draft of evacuation plans, the efficiency of evacuation in case of emergencies and the disposal of emergencies. Starting from the integrated development of Bohai rim megalopolis, Tianjinâ&#x20AC;&#x2122;s emergency transportation system guided by the world city by Tianjin and Beijing, will realize the building and sharing of the infrastructures. At present, Beijing-Tianjin corridor enjoys good traffic conditions, which includes Beijing-Tianjin-Tangshan expressway, Jingjin expressway, Beijing-Tianjin intercity railway, Beijing-Shanghai high-speed railway, Jingshan railway and Beijing-Tianjin highway, but obviously lack of channels in edge of north and south district. To improve the overall capacity, we should enhance the traffic corridor with the built of the second airport of Beijing which connects to Tianjin Nangang, Jinghai and Langfang by the south and has only one traffic routeâ&#x20AC;&#x201D;Tianjin-Shanxi highway that connects to 112 highways. And we should strengthen the contact between Beijing airport and Baodi, Hangu and strengthen the direct traffic links. 3.4 Establishing Public Safety Management System Based on Regional Cooperation and Coordination (1) The shift of public safety management from

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single disaster management to full management covers the draft of integrated strategy, policy, disasters management plan, arrangements and support system of resources; (2) The risk management of public safety should run through the whole process of the disasters. In case of no disasters, we should conduct daily risk management, namely prevention and preparation, during the disasters, we conduct emergency risk management, namely, emergency and rescue. After the disasters, we conduct crisis risk management to restore and rebuild the city; (3) Public safety management places much emphasis on management integration of different parties (government, civil society, enterprises, international world and international organizations) to shape a mechanism of integrated leadership, cooperation, and sharing interests and responsibilities. It includes the integration of organizations, information and resources; (4) Public safety management should shift from pure crisis management to risk management and combine with daily public management of government; (5) For effective management of public safety, government should establish integrated performance indicators of public safety management. We should keep an eye on the occurrence and change of disaster risks, and provide full inspection to public safety management departments in terms of their purposes and methods, and the performance of staff and the main departments.

4. Conclusions Bohai Rim is one of the three major economic zones of China with the other Pearl River Delta and Yangtze River Delta. Bohai rim megalopolis is identified as one of the three most important megalopolis of china according to National Development Priority Zones Planning and is aiming to a world-class megalopolis. Tianjin is the important

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Study on Emphases and Trend of Tianjin Urban Public Safety Planning from the View of Bohai Rim Megalopolis

city in Bohai Rim area with the neighborhood of China capital Beijing. So Tianjin urban public safety planning includes not only comprehensive disaster prevention and reduction, effectively preventing and reducing disasters, ensuring the safety of the life and property of the residents, which is the main content of traditional public safety planning, but also sharing resources and facilities from the view of megalopolis, eliminating hidden area troubles, reducing whole environment risks and so on. And Tianjin should assume responsibility to perfect the contents and method of urban public safety planning from the view

of region.

References [1]

[2] [3]

[4]

Research on Comprehensive Disaster Prevention Planning in Tianjin Urban and Rural District, Tianjin Urban Planning and Design Institute, 2010. Research on Tianjin Urban Public Safety Planning, Tianjin Urban Planning and Design Institute, 2012. Tianjin Urban Planning and Design Institute, Research on Space Developing Mode of Bohai Rim Megalopolis, Tianjin Planning Bureau, Tianjin Planning Academy, 2011. W.J. Shi, Research on space developing mode of Bohai rim megalopolis, Bohai Economic View 10 (2011) 3-9.

Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1209-1219 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

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Improving Conviviality in Public Places: The Case of Naples, Italy Gabriella Esposito de Vita1, Carmelina Bevilacqua2 and Claudia Trillo3 1. IRAT National Research Council of Italy (CNR), Naples 80134, Italy 2. Department of Heritage, Architecture, Urban Planning (PAU) University Mediterranea, Reggio Calabria 89124, Italy 3. School of the Built Environment (SOBE), University of Salford, Salford M54WT, UK Abstract: Under the umbrella concept of conviviality in public spaces, a research project on the rehabilitation of urban areas for commercial and retail uses—as engine of a complex process of production of places for social and cultural mixité—has been defined. The aim of this research has been to produce useful tools for coping with the abandonment of public spaces in former commercial urban areas, without generating anonymous and globalized commercial districts. Through involving local stakeholders in a participatory process, the first phase of the research here presented needs to demonstrate the possible effectiveness of a pilot action plan in dealing with both isolation and gentrification processes of historical centres. The main hypothesis is that traditional retailers should be considered an essential element to ensure effective public use of urban public spaces. The research methodology is based on a qualitative approach. Focussing on the process of impoverishment within local commercial districts, the research group started working with local stakeholders in order to identify priorities and criticisms for enhancing a regeneration process. The case study to be carried out in Naples is the historical market place of Piazza Mercato in the Città Bassa of Naples (Italy). Key words: Public places, traditional retail areas, urban regeneration, historical centres, conviviality, Naples.

1. Introduction The contemporary city is affected by a profound crisis due to the loss of cultural identities, of traditional social networks and of welcoming urban spaces for improving interactions between diverse components of society [1]. Places of public life are the expression of this scenario: the agora is changing forms, functions and symbols, following new trends superimposed by globalization phenomena [2]. The impact on the transformation of public places due to recent dynamics, is revealed by the tendency to produce market-led transformations of public places in affluent areas and the abandonment and decay of the peripheral public realm [3]. In the following pages, a research project will be presented which is aimed at identifying the main components of a process of rehabilitation of urban Corresponding author: Gabriella Esposito de Vita, Ph.D., researcher, research fields: urban design, community planning and social activation. E-mail: gabespo@unina.it.

areas for commercial and retail uses in order to favour social and cultural mixité and economic regeneration. The project deals with the increasing globalization process, and consequently with the expulsion of traditional and identitarian commercial activities from the city centre, creating ruptures in the continuity of the urban grid in terms of creation of market-led and anonymous commercial areas on the one hand, and in terms of abandonment and decay of less affluent areas with a strong local cultural character on the other [4]. The research starting point is the role played by traditional retailers and artisans as an essential element to preserve local cultural character, ensuring effective public use and liveability of urban public spaces. The privatization and commercialization of public and quasi-public places in affluent or well-connected areas of the city, on one hand, and the decay and abandonment of public places in deprived areas, on the other hand, they are both causes and effect of the social transformations. Economic crash,

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Improving Conviviality in Public Places: The Case of Naples, Italy

transformation of the job-market, dynamics and quantities of migratory flows are strictly related to the tendency of living in gated communities and privatized public places dedicated to a forced conviviality. The idea of convivium could be the umbrella concept for surveying, interpreting, assessing, designing, managing public spaces as places of multicultural identity, security and security perception, democracy and discussions, ethic and aesthetic and human development [5]. This qualitative approach aims at defining a holistic methodology for interpreting, designing, managing and assessing the refurbishment and redevelopment of those specific areas. This topic will be addressed by developing an urban design tool based on an effective participatory process in the rehabilitation and redevelopment of public places in abandoned commercial areas [6]. This tool could be applied within community planning consolidated methods [7-9], in order to better address the physical and spatial component of the mapping and visioning process. Consolidated procedures for collecting and sharing the demand expressed by local communities in terms of services delivery and public places organization have been developed in different fields of knowledge [10]. Nevertheless, there is a lack of procedures for addressing demand for spatial transformations in order to favour the preservation and development of traditional and identitarian artisanal and retail areas as a driver for a wide urban regeneration process [11]. In order to identify the way physical and functional transformations of commercial areas in city cores can favour results in terms of social cohesion, economic development, cultural preservation and local liveability, the study started by working with a case study approach [12]. The research focuses on the specific experience of Naples in southern Italy, which offers a wide range of interesting fields of reflection on the research topics. The group of scholars and local technicians involved in the fieldwork started doing active observations of

the Neapolitan urban area in order to identify possible significant case studies to be carried out. The conceptual map of significant areas was discussed with local key actors such as: academics in the field, technicians involved in the urban planning and management, members of the local governing bodies, activists from local NGOs (non-governmental organizations) involved in topics such as job creation, civic activation and urban regeneration as well as local communities. The discussion resulting in the selection of the historical market place of Piazza Mercato and its neighbourhood in the Città Bassa district as a case to be analysed because of the specific issues related to artisanal and retail traditions combined with the abandonment of public places and the impoverishment of economic activities on the one hand, and because this area has been the core of the Local Action Plan implemented within the framework of the CTUR and Hero Projects of the URBACT II Programme. The fieldwork has been developed according to the rationale of the EU-funded research “Commercial Local Urban District Programme” led by the PAU of the University Mediterranea of Reggio Calabria (IT) “aimed at emphasizing the strategic role of small retailers—handcraft and typical food—in reinforcing the sense of community, reducing transportation costs and contributing to the creation of an attractive urban environment, thus producing an increase in private investment” [13]. Through the experience gained during the execution of the Local Action Plan for this historical area in southern Italy, this paper aims at introducing and discussing a work in process oriented to coping with the tendency to abandon wide core areas of the city centre by supporting virtuous processes of urban regeneration, and intervening through a participatory process in the rehabilitation of traditional and natural market areas. This paper is divided into four sections. Having introduced the research in this section, the following three sections aim to:

Improving Conviviality in Public Places: The Case of Naples, Italy

• Set the context to identify the theoretical and methodological context of urban design, community planning and economic procedures to be applied together to commercial urban districts regeneration; • Define the framework for the empirical analysis and discuss the pilot area findings; • Draw general conclusions, defining the role of local commercial areas as divers of urban regeneration.

2. Setting the Theoretical and Methodological Context Every city is a human creation, but only a few cities—in certain historical moments—have developed a successful expression of public spaces as trans-community agora suitable for liberating identity. In those cases, cultural cross-pollinations have led to the creation of particular architectural and urban forms, which generate a physical-functional-relational milieu [14]. “Public space, if organized properly, offers the potential for social communion by allowing us to lift our gaze from the daily grid, and as a result, increase our disposition towards the other” [15]. Shared spaces have played, on the one hand, the role of symbols of collective well-being and formation of civic culture and, on the other hand, of agonistic struggle and social conflicts. “In an age of urban sprawl, multiple usage of public space and proliferation of the sites of political and cultural expression, it seems odd to expect public spaces to fulfil their traditional role as spaces of civic inculcation and political participation” [15]. The history and culture of European cities reveal the importance of public spaces such as streets and squares, which are deeply influenced by the commercial functions they host. Over the centuries, local retailing models, often integrated with the production of typical services, handcraft traditions and locally produced food, have frequently conditioned forms and organization of the European city (Fig. 1). More generally, a higher level of manufacturing,

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commercial and residential integration, is still related to vibrant urban environments, which are rich in urban life and social relations [16]. The contemporary public space is the urban place that, more than others, has been influenced by recent transformations of production-related activities and of human behaviors, spatial codes and use models of public spaces—for a long time completely unchanged—have been affected by the acceleration of the dynamics of the urban system [17]. In accordance with Habermas’ observation that “public spaces become the object of practices of cultural representation, with which the public sphere is arguably more and more concerned” [18], the research deals with the holistic idea of public places as an expression of the cultural gaps within a conflicting society and, at the same time, as place for improving conflict-solving practices by favoring public gathering. The first node to be tackled is the lack of a shared vocabulary concerning the recent expressions of public spaces, of private spaces with a public use and of public spaces with a private use [19-22]. Some provocative questions could be evoked, as the editors did in Architecture and Dispersal: “What constitutes public space in the contemporary city? Can the public sphere still exist in the urban context? Should public space be fought for by architects and urban designers?” [23]. The everyday use of public space has been changing from necessary uses to optional, recreational uses. This changing role increases the need for appropriate, well-designed places in which people choose to spend time, and that provide a place for people to relax, socialize and be part of urban life” [24]. From the social point of view, it is widely recognized that integrated urban environments often contribute to a higher level of safety because of the social control exercised on the public spaces due to their continuous use, for the same reason, they are less likely to became blighted areas, thanks to the involvement of local communities in preserving their values [25, 26].

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Improving Conviviality in Public Places: The Case of Naples, Italy

(a)

(b)

(c) (d) Fig. 1 The European city: (a) Commercial areas in the city centre of Eltville am Rhein (2008); (b) Castle Valentino Park in Turin (2011); (c) a square in Venice (2010); (d) the refurbished transport node of Montesanto in the historical centre of Naples (2009) (Photomontage by the authors).

From the environmental point of view, the residential and commercial balance in each area is a fundamental tool in securing a less car-oriented living model, as small retailers allow residents to meet their everyday needs by walking, thus, it represents a real and proper pillar in ensuring a sustainable urban lifestyle [27]. Furthermore, the link between small retailers and niche local production helps to ensure a more consistent and efficient supply chain, avoiding useless freight transportation costs, as well as reinforcing the relationship between the urban and rural environments [28]. Although these are remarkable and valuable features in the traditional European urban model, nowadays the changes in the international retail organization system are deeply impacting on the commercial functions of some urban areas. In

particular, shopping malls and other large shopping centres present potential forces for dramatically reshaping the urban and suburban landscapes. The research project, starting from the theoretical perspective described, aims at defining a participatory process to physical rehabilitation and social-economics regeneration centred on the enhancement of local art-and-crafts and retail traditions. The participatory process needs to be developed through involving local stakeholders such as: local authorities, entrepreneurs, retailers and artisans, representatives of local services, developers and planners, academics involved in research and education activities related to the area and representatives of local communities. The conceptual framework consists of the possibility of merging urban design, community

Improving Conviviality in Public Places: The Case of Naples, Italy

planning and economic procedures in order to build a new tool for renovating degraded public spaces and improving the attractiveness and accessibility of deprived urban areas by focussing on the high potential of local commercial activities. The research can assist policy-makers in coping with the needs of urban regeneration by setting up an analytical process to understand how a public-private partnership oriented to sustain local retail can be both market-led and social-led. In the 1990s, the PPPs (public-private partnerships) have been considered as a key tool of public policy across the world [29]. In some cases, PPP (public-private partnership) can be considered as a cooperation between public and private sectors for developing services through risk and cost sharing. In other definitions, PPPs are informed on a mutual commitment between a public sector organization with any other organization: from non-profit NGOs to private companies market-led. As concern the balance of roles among partners, in PPP’s both public and private parties share costs, revenues and responsibilities [30]. There are different forms of mutual commitment, of cost and revenue sharing and of subjects participant in PPPs oriented to regeneration processes [31]. In Italy in the 1990s, the planning culture has been massively interested with the integrated programs experience [32], and the definition of partnerships between local administrations (such as city council) and developers and other investors on the private side. The research starts by highlighting integrated approaches related to credit access, local resources promotion, job creation, typical retail protection and community engagement—in order to understand how the territorial milieu can contribute to create the necessary critical mass for improving local urban regeneration initiatives [33]. In so doing, the development of the case study approach has been conducted under the umbrella of the Local Action Plan implemented within the

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framework of the CTUR and Hero projects of the URBACT II Programme in Naples.

3. Case Study Analysis: The Local Action Plan of Naples Città Bassa The research here presented has been developed along diverse routes for empirical applications. In particular, two projects guided by local administrations and oriented to make possible a wide public-private partnership have been chosen to cross the theoretical premises with a case study approach. The projects “Cruise activity and the recovery of urban and harbour building heritage: strong elements of the common interest of sea towns to develop and strengthen the urban tourism sector” (CTUR) and “Heritage as Opportunity” (Hero) of the URBACT II Programme [34] have been both developed (2008-2011) by a network of European cities. The core idea of the first one has been to improve competitiveness and liveability of port cities through the waterfront revitalisation (including derelict industrial areas) in an overall approach of the port city development, creating a mix between maritime and urban activities within the framework of an integrated approach of sustainable development. The second project—dealing with the challenging management of historic towns in Europe—focuses on heritage cities throughout Europe, in order to enhance balance between the safeguarding of heritage and the development of the city, taking heritage as an economic driver. These projects are both completed and are now in the process of being implemented in the local policies and are the base of the new projects promoted by the Neapolitan City Council in order to deepening the concept of land consumption in the historic centre. Briefly, Naples can be considered one of the prominent ancient settlements in Europe and part of the Mediterranean basin (Table 1). Its historic centre is a unique example of architectural stratification through the centuries and is still a vibrant catalyst of

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Improving Conviviality in Public Places: The Case of Naples, Italy

mixed activities without any museumification phenomena. Along with these positive aspects there are many problems, such as the high population density, the low education indexes, the severe status of the labour market linked to the lack of private activities and job creation initiatives, the presence of criminal organizations and the strong rehabilitation needs of the built environment, including the cultural heritage. The complexity of this local scenario of resources and challenges is the humus for nourishing the local initiatives we have chosen as paramount cases to be described [35]. The first step has been the definition of the case study domain in terms of location, size, functional organization and general characteristics. Through the dialogue with the Urban Planning Department of the City of Naples, the active observations in different daytimes, weekdays and seasons as well as the discussion with local stakeholders and scholars in charge, a specific area involved in these comprehensive projects has been chosen in order to address the topics of the research. The coexistence in the same area of various urban planning and management tools, of several UE-funded initiatives as well as of grassroots movements and of traditional local economic activities can be considered the ideal scenario for developing a complex participatory process of urban regeneration to be tested and generalized. The research in progress here introduced has been developing in parallel and—on some topics—in cooperation with the planners in charge for the cited URBACT projects conducted by the City of Naples (Table 2). The area of Città Bassa, despite having previously had a strong commercial character, suffers since the end of the Second World War relative neglect and gradual decay. In this context, some relevant key issues can be pointed out with regards to: the physical aspects such as location, accessibility, built environment conditions, cultural issues such as

historical heritage, monuments, arts and crafts traditions; and social scenario in terms of social deprivation indices (Table 3). The work is premised on enhancing local revitalization and regeneration processes by focussing on the potential of an integrated approach to commercial activities, among the key issues related to the urban revitalization of the historical urbanscape. This is to be addressed in Naples by meeting the needs of different stakeholders—the linkage with the cited URBACT projects is “to secure traditional shops and retail trade structures as these ones are struggling to survive and to set up new governance structures for a better coordination of the revitalization activities” [34]. The focus area for Hero projects is Piazza Mercato, which is connected to an overall URBACT LAP named “Città Bassa” [34] included in a comprehensive intervention called “The waterfront of the historic centre and port area from piazza Municipio to piazza Mercato: a sustainable development through the improvement of the cruise tourism impact”, which also concerns the LAP of the URBACT Thematic Network CTUR (Cruise Traffic and Urban Regeneration) lead by the City of Naples [36]. The area of Città Bassa of Naples reflects all the issues, criticisms and potentiality related to the integration of typical handicrafts, dense residential uses, traditional commercial activities and the historical character of public places. This wide and articulated area lies between the port and the historical centre which has been listed as a World Heritage Site by UNESCO since 1995 (Fig. 2). The study area is included in the range of influence of the Local Action Plan built by the city with the help of its LSG (local support group), within the framework of the URBACT projects. The LSG as defined by Hero is to support the development and implementation of the Integrated Cultural Heritage Management Plan, which is “oriented towards the needs of the historic urban area and its users, offers the unique opportunity to bring the different stakeholders

Improving Conviviality in Public Places: The Case of Naples, Italy

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Table 1 Naples at a glance. Classification Location First settlement Population Pop. density Unemployment rate Income per capita Historic centre

Properties Capital of the Region of Campania—Southern Italy VI century B.C. as a Greek settlement 1,004,500 inhabitants (City Council of Naples, census 2001) 8,556 inh/sq km (City Council of Naples, census 2001) 31.39% (City Council of Naples, census 2001) €25,565.81 (Finance Ministry, 2009) UNESCO recognizes the OUV (outstanding universal value) of the historic centre of Naples (1995)

Table 2 Plans and programmes which coexist in the study area. Plans and programmes

They connected to the ERDF 2007-2013

Study area DOS (Strategic Guidance Document) Integrated Urban Plan EUROPE for the historic centre of Naples (PIU EUROPA) Grande Programma UNESCO (UNESCO Great Programme) Strategic Plan of Naples Hero “Naples Historic Centre World Heritage Site Management Plan (WHSMP)” “Project of renewal of Borgo Orefici” under 2000-2006 ERDF Funds

Table 3 Città Bassa: some relevant aspects. Classification Location Accessibility

Historical heritage

Art and crafts tradition

Social deprivation

Built environment

Properties Enclave between the port area and the historic centre UNESCO WHS 15 km from Capodichino International Airport Near the Central Railway Station Served by four metro stations (2 of those need to be completed) Near the local and regional maritime transportation nodes of Beverello Quay and Porta di Massa Quay Porta Nolana gate of the ancient city walls The renaissance church of SS. Cosma e Damiano The ruins of Castel del Carmine The baroque church of Santa Maria del Carmine Sant’Eligio Maggiore Church of the Angevin period dated 1270 Borgo degli Orefici (goldsmith quarter) since the fourteenth century Piazza Mercato Old Marketplace Antiche Botteghe tessili (textile market) Typical handmade street food Unemployment rate (Mercato district 38.01%, Pendino district 40.37%) Illegal immigration Hidden and informal economic activities Low level of housing maintenance and technological retrofitting Abandoned and decayed public places Lack of spaces for pedestrian uses due to cul-de-sacs, squares transformed in parking areas, inefficient street lighting, abandoned ground floors (38% unused sqm—source Si.Re.Na Company) Buildings which provide physical and visual barriers between the area and the waterfront

together” [34]. The Neapolitan LSG has been formed as the first step of the URBACT projects and has become the main interlocutor of the different kinds of local initiatives such as research fieldworks, entrepreneurships, training and programmes for the control against informal and hidden economy. The fieldwork here presented has been oriented to: • Collect, analyse and compare the initiatives

promoted within the EU-funded projects CTUR and Hero with the other top down initiatives promoted by the City Council of Naples; • Develop a session of active observations, informal interactions with people met in the area, morphological analysis; • Participate in focus groups, local initiatives, meetings with local stakeholders;

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Improving Conviviality in Public Places: The Case of Naples, Italy

• Discuss with local stakeholders the results of the LAP activities and the relevant questions emerged through participation in the activities of the LSG. The results of this fieldwork could be summarized in the general idea that the LAP (Local Action Plan) of Naples Città Bassa could become an experience of paramount importance due to its mixed and complex character (Table 4). Focussing not only on social indices and economic issues, the added value of the LAP can be considered the capacity of integrating both the approaches: built environment and historic heritage rehabilitation on the one hand and economic strategies on the other. Within the LAP of Naples Città bassa emerges a strategic approach in focusing on the reconnection of the historical city centre with the harbour as engine for enhancing the vitality of the commercial district included in the area. The economic stakeholders (retail consortia, artisan consortia, shipping developers, building developers) suggested to enhance the LAP through collecting

resources in order to support the specific rehabilitation projects included in the plan. The priorities emerged are: the development of sustainable tourism, the creation of business incubators related to the traditional artisanal and retail activities of the area, the increasing of commercial attractiveness through enhancing accessibility to the area, and job creation in specialized fields. From both the economic and social side, the stakeholders involved have identified as result obtained by the LAP the impact achieved at the local level by transferring the knowledge acquired in the URBACT process to local policies, programmes and actors. This has been accomplished by scaling-up some of the action plans at the policy level and integrating them into mainstream services, as well as by securing funding through the Operational Programmes of the ERDF (European Regional Development Fund) for their implementation (Table 5). Every subject interviewed agrees that the process has also contributed to creating new partnerships between

Fig. 2 The study area of Città Bassa of Naples and Piazza Mercato (Courtesy Stefania Oppido).

Improving Conviviality in Public Places: The Case of Naples, Italy

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Table 4 Città Bassa LAP: main aims and objectives. No. 1 2 3 4

Main aims and objectives Requalification of the waterfront monumental area and nearby historic urban area Refunctionalization of the city and the port heritage Maximize the economic and social impacts of the projects Support the social and economic development of the “Città Bassa” quarter based on historical activities

Table 5 Città Bassa LAP: flagship projects investments (CTUR and Hero). Projects Cultural heritage safeguarding—building restoration Old Monastery Carminiello (School) S.Eligio Monastery Borgo Orefici requalification S.Maria Portosalvo Church Public places requalification Requalification of complex ambit in the area Underground parking and requalification of related areas Business incubator for goldsmith and textile activities

Responsible

Funds allocated

Source

City of Naples

3,000,000 2,500,000 17,670,000 1,200,000 5,140,000 10,000,000 13,500,000

ERDF 2007/2013

SiReNa Private City of Naples

City of Naples Private consortia

Tramlines and requalification of via marina

City of Naples

Shuttle connection to the maritime nodes

Port Authority of Naples

1,000,000 4,203,491 13,997,299 750,000

Public/private Private ERDF 2007/2013 ERDF 2007/2013 ERDF 2007/2013 ERDF 2007/2013 Private funds ERDF 2000/2006 Public/private funds Port Authority of Naples

Sources: Hero Flagships Projects 2011 and CTUR Naples Local Action Plan [37].

different levels of government and the involvement

elaborated and discussed with local stakeholders.

and participation of private stakeholders in the

Starting from the virtuous process launched within

development of the project. The LAP has been

the framework of the URBACT LAP here analysed

developed through the active participation of different

and applying the methodological premises of the

categories of local stakeholders, designing a new

CLUDs project, an adaptive model of urban

possible structure of PPP.

regeneration based on commercial activities is

4. Conclusions The complex and articulated scenario of PPP tools offers the possibility of identify a possible dynamic system of relationships between subjects, actions, resources, roles and evaluation of the results. In particular, the case study approach is needed to design a sort of fuzzy-architecture of the partnership models aimed at facilitating local private and public initiatives within the framework of the common interest of generating social and economic enhancement. A bottom up approach, oriented not only to collect demands and needs from the territory but also to encourage private initiatives, start-ups, non-profit organizations, and other forms of investments, will be

currently being defined—in cooperation with the local stakeholders involved in the transformations of the study area. Evidences from the fieldwork states that in specific conditions local traditional commercial areas could play an important role as drivers of urban regeneration and cultural enhancement. The conditions identified are: • The former or current presence of local art & craft and/or cultural traditions that could be the media for enhancing the collective sense of belonging to the area and building the critical mass for developing a regeneration process; • The activation of bottom up (predominantly private) and/or top down (predominantly public)

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Improving Conviviality in Public Places: The Case of Naples, Italy

projects oriented to support local initiatives in terms of social activation, job creation, place branding, public places rehabilitation;

bottom up approach by creating the humus for

â&#x20AC;˘ The participation of local economic and social stakeholder to the decision making process in order to better address priorities and resources.

rehabilitation of commercial areas in a wide profitable

In the context analysed, the LAP has been

according to the CLUDs rationale, the investigation of

considered an important instrument for merging

the potentiality of the territorial milieu in enhancing

together the above conditions and for encouraging the

the building capacity of the commercial local districts

dialogue between the stronger stakeholders of the

in the city core.

LAP area, such as the Port Authority, the City Council and the other public actors involved on one side, and the communities, the arts and crafts private consortia, the developers and the port operators on the other side. By setting up the local support group, the URBACT projects acting in the area have created a positive process: first, the initiatives developed by public bodies started the auditioning process and the collection of resources; subsequently, private bodies and civil society have become part of the process. As we can see, in the LAP experiences analysed, the initiative starts with the involvement of public bodies whose activites are primarily oriented to identify priority for public investments and to engage other public and private stakeholders. This process has been developed by the City of Naples and the LSG using a wide participatory process involving different categories of city-users, producing a huge data and information collection from the territory, providing a big effort in terms of sourcing and integration of financial resources and involving different categories of city-users. The institutional architecture of the partnerships between public and private actors in the area and the relationships between these partnerships and the projects funded in the area depends on the National Operational Programme of the Campania Region funded within the ERDF 2007/2013. The LAP can be considered the process for bringing together the local initiatives with the main flagship projects funded by the public sector, in order to enhance the results of this

nourishing the non-profit private initiatives of urban regeneration

driven

the

development

and

and marketable way. The next step of this ongoing research should be,

Acknowledgments This presentation draws from the cooperation between the research program CLUDs funded within the framework of the EU IRSES Marie Curie 7FP and the Urban Planning unit of the National Research Council of Italy (CNR-IRAT).

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Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1220-1228 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

DAVID

PUBLISHING

Design Drivers for Affordable and Sustainable Housing in Developing Countries John Bruen1, Karim Hadjri2 and Jason von Meding3 1. School of Planning, Architecture and Civil Engineering, Queen’s University Belfast, Belfast BT9 5AG, UK 2. School of Built and Natural Environment, University of Central Lancashire, Preston PR1 2HE, UK 3. School of Architecture & Built Environment, University of Newcastle, Newcastle 2308, Australia Abstract: Current demand for housing worldwide has reached unprecedented levels due to factors such as human population growth, natural disasters and conflict. This is felt no more so than in developing countries which have experienced disproportionate levels of demand due to their innate vulnerability. Many current approaches to housing delivery in developing countries continue to utilize inappropriate construction methods and implementation procedures that are often problematic and unsustainable. As such affordability and sustainability are now vital considerations in the international development debate for housing the poor in developing countries in order to meet the long term sustainable development goals and needs of housing inhabitants. This paper utilized an extensive scoping study to examine the various facets impacting on design decision making relative to sustainable and affordable housing delivery in developing country contexts. Aspects of affordability, sustainability, design decision making, appropriate technology use, cultural awareness, as well as current barriers to affordable and sustainable construction in developing countries are examined in detail. Results highlighted the capability of indigenous knowledge, skills and materials as well as selected appropriate technology transfer and cultural awareness by foreign bodies can be utilized in innovative ways in addressing current housing needs in many developing country contexts. Key words: Sustainable housing, low-cost housing, design decision making, affordability.

1. Introduction Shelter is one of the most basic human requirements for survival. The provision of adequate and appropriate housing can be deemed to address this basic need. However, the provision of adequate housing also meets more than human’s immediate needs and has the potential to contribute significantly to a wider social, environmental and economic context and to a better quality of life and personal fulfillment for its inhabitants through aspects such as employment generation, knowledge transfer and training, value and cultural continuity and improved health conditions [1]. However, the struggle for adequate housing in many developing countries is considerable and set to continue to rise in future Corresponding author: John Bruen, B.Sc., B.Arch., M.Sc., RIBA chartered architect, research fields: post disaster management and sustainable housing. E-mail: jbruen01@qub.ac.uk.

decades unless addressed. As such housing is central to much international debate in many developing countries. Vast numbers of people find themselves without adequate shelter due to housing shortages experienced in many of these areas and this is well documented in current literature [2-4]. However, much of the current literature highlights various aspects that impact on the provision of housing in various developing country contexts worldwide without focusing solely on dwelling design and the aspects that impact the designers decision making, i.e., the barriers and drivers of design. This paper provides findings from various developing country contexts to enable the identification of common aspects that impact designer’s decision making in various developing country contexts worldwide. Tipple [5] states that it is almost impossible to determine the exact shortage of housing

Design Drivers for Affordable and Sustainable Housing in Developing Countries

in the developing world due to limitations such as insufficient data, little agreement on units of measurement, the length of time data takes to collate and publish and data going out of date very quickly. Housing shortages can often be traced back to two main sources as follows. 1.1 Pace of Growth of Developing Countries, Governmental Policy and Countries History The pace of growth and industrialization in many developing countries has led to rapid urbanization and increases in population. The UNCHS (United Nations Centre for Human Settlements) estimates 95% of the world’s total population growth in the last decade has occurred in developing countries and that these

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total of 182 million people were made homeless. Of these natural disasters a total of 98% of the 211 million people affected annually from 1991 to 2000 were in developing countries [2]. The devastation caused by many of these scenarios involves the destruction of much of an area’s built environment, i.e., housing (shelter), hospitals, shops, schools etc., services infrastructure (water supply, heat and sanitary requirements) transport infrastructure (roads, rail). The destruction of these basic human requirements has many consequential types of fallout such as health, economic and social upheaval in the affected country.

2. Methodology

countries will contribute 2 billion new residents

As the research area is quite broad a scoping study

during the next 25 years [3]. Between 2007 and 2025,

was selected as the most appropriate research method

the annual urban population increase in developing

for this review in order to summarize the key findings

regions is expected to be 53 million compared to 3

from all available literature and also to identify the

million in developed regions [3]. This increase has

potential gaps. This approach is particularly relevant

already resulted in severe housing shortages, urban

to this particular study as there are numerous sources

poverty and homelessness in many countries and the

of information available from various organizations

development

and bodies, i.e., academic journals, industry journals,

slums/shanty

towns/informal

settlements on the periphery of many major cities. As

international

housing

organizations,

NGOs

a result, slum dwellers now represent more than 50%

(non-governmental organizations) etc.. In-depth and

of the population in many developing countries with

broad findings on the topic were sought from current

close to 1 billion people, or 32% of the world’s

available literature to enable conclusions and findings

current urban population, live in slums in inequitable

to be disseminated to relevant stakeholders who may

and life-threatening conditions [3]. As such, the

lack the time or resources to undertake the study

informal sector is recognized as the biggest producer

themselves i.e. designers, policy makers, community

of housing in many developing countries [4].

organizations, NGO’s. Arksey and O’Malley [6] state that scoping studies are appropriate in this context as

1.2 Natural Disasters and Conflicts The devastation resulting from natural disasters and conflicts is most frequently observed in developing countries due to innate vulnerability and lack of knowledge and resources to adequately implement disaster mitigation strategies or post disaster/conflict recovery strategies. Between 1974 and 2003, 6,367 natural disasters occurred globally, causing the death of 2 million people and affecting 5.1 billion people. A

they are guided by a requirement to identify all relevant literature regardless of study design as opposed to been guided by a specific research question as may be the case in a systematic literature review. A five point framework developed by Arksey and O’Malley [6] was utilized for this scoping study. This framework firstly consisted of developing a research question, secondly identifying the relevant literature,

1222

Design Drivers for Affordable and Sustainable Housing in Developing Countries

thirdly selecting the relevant literature, fourthly charting the data and finally summarizing and reporting the findings in a concise manner. The selected research question was broad in nature to cover the main aspects to be covered by the study: â&#x20AC;&#x153;What are the main barriers and design drivers for affordable and sustainable housing in developing countries?â&#x20AC;? In keeping with Arksey and Oâ&#x20AC;&#x2122;Malley [6] proposed framework and in order to generate a broad range of coverage an extensive approach using selected keywords was utilized to identify relevant data. This consisted of journal publications searches in major registers such as Avery, INFORM Global, Zetoc, Web of Science and Compendex. A further internet search using Google Scholar was utilized to further expose publications or grey literature. Bibliographies and references were studied to locate further useful information for the study. Website searches of suitable reputable organizations such as Un-Habitat, national and international housing NGOs, housing charities and open access journals, were examined for relevant information, i.e., field reports, policies, case studies etc.. The latter approach is quite a relevant data collection method in relation to this particular topic as open access to information and knowledge transfer, with the aim of improving housing for the poor in developing countries, is an aspiration of many organizations operating in the field of housing provision in developing country contexts and the making available of their information is to be commended. Following elimination of irrelevant studies a total of 649 references were identified from the various searches outlined. Following further in-depth reading of titles and abstracts 154 were selected for further reading of which 55 were used in the final reference list. Mapping of the findings were divided into various headings and sub heading to address the overall research question. The overall main headings consisted of: (1) barriers and challenges to sustainable

construction in developing countries; (2) main design drivers with the potential to contribute to affordable and sustainable housing in developing countries.

3. Current Approaches to Housing Design and Delivery The two main causes of housing shortages outlined share many commonalties in that in both situations should the housing shortage be addressed using conventional unsustainable construction techniques then the environmental effect alone of this approach would be devastating considering the vast scale of housing required in developing countries. While the majority of efforts by decision makers such as governments, NGOs, CBOs (charity based organizations), etc. to address housing shortages have the best intentions of people central to their efforts, the literature highlights that the current approaches to housing shortages often involve a top down approach. This means that many communities are not involved in participation to the level that they should be to ensure their short and long term settlement needs are satisfied in an appropriate manner. The global shortage of housing requires appropriate, affordable and sustainable responses that cater to severely affected regions worldwide. Erguden [1] highlights that policies and approaches for housing in developing countries have evolved over the past number of decades from one centered on government provided social housing to one of self-help to the current common approach of enablement in which all parties support a people centered housing process to obtain housing delivery goals. Although the enablement based approach is generally considered to be the most appropriate many approaches currently fall well short of the desired aspirations in relation to affordability and sustainability. Reffat [7] states that the concept of sustainability has only recently been introduced into developing countries construction industries and that sustainability and sustainable

Design Drivers for Affordable and Sustainable Housing in Developing Countries

construction are not yet an essential part of the decision making process. Traditionally, affordability in mainstream housing markets is associated with economic and social sustainability with little emphasis on environmental sustainability [8]. Perceived higher costs and underlying socio-cultural factors also contribute to the lower levels of social acceptability of sustainable construction in the main stream affordable housing market [9, 10]. Global inequalities and economic constraints in many developing countries have also resulted in pragmatic governance decision making in relation to sustainable social and environmental goals being made more difficult [11]. In many instances, organizations have to provide housing to meet the immediate term shelter needs of large populations, at times due to natural disasters or conflicts, and this is often given priority over long term aspects such as sustainable design, participation and reference to local materials and techniques. Sustainability is thus often perceived as an additional cost to standard practice and is not a necessity but rather a luxury of the rich [7, 12]. Many current approaches to housing provision are left to what professionals from the formal sector and international bodies consider the most appropriate solution which is often at odds with the expectations of the future house inhabitants and environmental ideals [13, 14]. Many current approaches often employ a one hat fits all or quest for a universal approach to addressing the current housing shortage in developing countries. Often these approaches involve imported industrialized materials, western construction techniques and typologies not common to the surrounding context. This is often due to the perception that the “west knows best” and these solutions are deemed to be associated with wealth, progress, prosperity and globalization. This is a flawed belief and demonstrates a clear lack of understanding and vision on behalf of the different decision makers involved in implementing these approaches. This often results in rigid monotonous

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constructions and typologies which ironically can have negative effects on the end users long term needs and wellbeing, i.e., replacement of traditional settlements with modern towns and lack of cohesion between the town’s inhabitant leading to socio-cultural and economic negative effects [15]. The manufacture and import of many of the materials used also result in houses that are not affordable for the masses of population that require them [16] as well as being environmentally unsustainable.

4. Barriers and Challenges to Sustainable Construction Various literature [4, 17-25] highlights the common barriers faced in trying to implement sustainable construction in developing countries: • Environmental sustainability is often a low priority in developing countries, and the need for immediate shelter is primary for the majority; • Psychological and sociological issues in relation to use of alternative materials and its acceptability by people, i.e., status of certain materials deemed for the poor only; • Effects of globalization and desire of many to imitate housing approaches of the west leading to inappropriate imported typologies, materials, designs etc.; • Lack of overall holistic approach to sustainable design, i.e., social, cultural, economic and environmental; • Lack of training and education in sustainable design and construction leading to lack of necessary design and building skills available; • Lack of access to adequate information and knowledge on sustainable development and design; • Inadequate government planning and policy making; • Perceived higher cost of sustainable building approaches; • Scarcity of professional designers and project managers;

capabilities,

i.e.,

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Design Drivers for Affordable and Sustainable Housing in Developing Countries

• Lack of demonstration examples of best practice sustainable construction approaches; • Disincentive factors over local material production, i.e., government supplying alternative imported materials; • Need to develop cost effective construction technologies; • Building materials are becoming ever more expensive. Need to utilize locally available materials to suit local typologies; • Lack of guidelines available on selection of appropriate building approaches and packages, i.e., materials, methods, designs, equipment; • Unaffordable land and housing prices and lack of land tenure; • Inadequate housing finance systems; • Lack of support of small scale construction industries; • Inefficient strategies;

inadequate

implementation

• Lack of research and experimental findings; • Lack of implementation and promotion of research findings on appropriate approaches; • Gradual vanishing of traditional wisdom and knowledge on local material and construction techniques; • Historical legacies of race and class; • Lack of government or political backing to sustainable development; • Inappropriate procurement systems; • Inability to adopt best practice; • Bureaucratic impediments to the implementation of housing; • Inappropriate building regulations; • Lack of consultation and capacity building with housing inhabitants; • Poor housing management and planning policies at both a national and local scale in many countries. In order to address these barriers and challenges a clear and concise design approach is required to identify them from the outset of projects and propose

methods of enabling designers and other stakeholders to address them so as not to have a detrimental effect on the long term overall affordability and sustainability goals of the project.

5. Main Design Drivers with the Potential to Contribute to Affordable and Sustainable Housing in Developing Countries This study focused primarily on the design considerations of appropriate and suitable low-cost sustainable housing to meet current shortages. The literature indicates that in relation to the design of dwellings there are three main broad areas that offer the potential to significantly contribute to the provision of affordable and sustainable housing in developing countries. 5.1 Appropriate Design and Material Selection Efforts to address immediate housing needs should simultaneously address the long term needs and sustainability of the communities which they intend to serve in terms of social, economic and environmental sustainability [17]. The increasing demand for housing has resulted in an urgent need for crucial research into new design approaches and use of alternative materials in housing delivery [17]. Mehta and Beidwell [26] argue that increasing the quality of life in developing countries requires optimum use of local natural resources and labor over imported materials, increasing the potential for greater affordability. Material supply has been recognized by many as one of the main contributors to the provision of affordable and sustainable housing, contributing up to 70% of the total direct costs of housing construction [25, 27-30]. The use of localized materials, skills and construction techniques in design has the potential to dramatically reduce the cost of housing compared to westernized techniques, while simultaneously contributing to sustainable housing solutions [31-35].

Design Drivers for Affordable and Sustainable Housing in Developing Countries

5.2 Participation, Knowledge Transfer and Use of Appropriate Innovative Technology Specific to Developing World Contexts Despite the fact that over two thirds of the worldâ&#x20AC;&#x2122;s population live in developing countries, to date the developed world has led the way in global environmental destruction [36]. It is also developed countries that have dominated research in relation to sustainable construction, much of which is aimed specifically towards a developed country context. This has led at times to a non holistic approach to sustainable housing with technical cost reduction measures often employed to a large degree with little consideration given to what housing means for its users [37]. Many current approaches result in conflicting and competitive issues in technological economic sustainability verses cultural and social sustainability [18]. There is recognition that sustainable development approaches and technologies established in the west are not always desirable and the evidence shows that if not implemented correctly, these approaches will prove unsuccessful [24, 37, 38]. New approaches need to be adopted for the vastly different contexts within developing countries and local conditions, knowledge and culture must be given full recognition [39]. Participation by relevant stakeholders in all stages of the design and delivery process has been recognized as an appropriate approach to housing provision in developing country contexts [40-43] Knowledge creation, exchanging and sharing of skills, knowledge and experiences between the relevant stakeholders are recognized as effective approaches in ensuring technical, cultural, economic and environmental aspects of housing design and delivery are addressed in an appropriate manner [1]. The use of appropriate technology should work in conjunction with design and materials and should correspond to local conditions and culture and be durable, reliable, require a minimum of maintenance and be fit for modern living [27, 44].

1225

Plessis [4] argues that although the level of development required in developing countries may be a cause of despair it can also be seen as an opportunity to learn from developed nations, avoid the problems experienced by developed countries, and follow a more sustainable development path, of which housing will play a major part. In addition, Plessis [45] argues there is no clear guidance as to what sustainable development of the built environment means and how sustainable development can be incorporated into the decision making process, further adding that the academic debate in developed countries has little to offer except where applies to the hi-tech world of the West. She further states that in order for sustainable development to be effectively addressed societies can not isolate themselves and two way communication and dialogue between developing and developed countries is required. This sentiment is backed by Cole and Lorch [46] who argue that environmental issues require international cooperation in setting agendas, targets, assessments and standards as well as the sharing of sound environmental knowledge and practice. Much of what we know as transfer of knowledge is attributed to factors such as globalization and advanced technology and communications. However, Oliver [47] highlights that cross cultural transfer and exchange of knowledge and ideas has always existed, it is just that it has never existed at such an accelerated rate due to modern technology and globalization. Vellinga [48] notes that globalization and the transfer of technology between different cultures need not necessarily be a cultural treat and that cultural hybridity is nothing new, stating that the important factor that influences its acceptance and success is the opportunity to appropriate it to local traditions, ways of life, cultural values and customs. As such Vellinga [48] states that globalization can best be regarded as an infrastructure which facilitates the appropriate exchange and transfer of new ideas and practices including green technologies for the built

Design Drivers for Affordable and Sustainable Housing in Developing Countries

1226

environment.

utilized could offer the potential to significantly

5.3 Design Decision Assessment Tools

Making

Assistance

and

6. Conclusions This paper presented the findings of a scoping study examining the various aspects impacting on the design and delivery of affordable and sustainable housing in developing country contexts worldwide. The paper utilized various relevant information sources to identify the main design barriers and challenges operating

design and delivery in developing country contexts. The study focused on aspects of sustainability

Fray and Yaneske [49] suggest that the problem with many responses to sustainability is that decisions are made with limited knowledge and information. Building and construction play an important role in supporting sustainable development in developing countries and as a consequence the vast demand for housing is a significant issue that must be prioritized. However, it is recognized that the relationship between the two is a complex one and that an assessment framework and structured approach are effective methods to integrate sustainability into buildings in developing countries [7, 50]. Sustainable assessment tools to date have mainly focused on a developed world context [51] and focus mainly on technological solutions. Aside from established assessment tools from developed nations, i.e., BREEAM (UK), LEED (US), GBTool (Multi National), EcoHomes (UK) there is little in the current literature to demonstrate the existence of any main assessment tool specifically directed to sustainable housing in developing countries. However, the need to develop context specific assessment tools for developing countries that cater for a wider group of stakeholders has been recognized, given that existing developed country tools are not deemed appropriate [51-57].

designers

contribute to the provision of appropriate housing

housing

provision

developing country context face and should be aware of from the outset of their design projects. The study further recognizes three drivers for design that if

beyond environmental aspects alone and addressed aspects such as economic and social elements which all form the triple bottom line many experts associate with sustainable design. It is concluded that the aspects identified in this study can be addressed through an informed design decision making process which considers the various design challenges, barriers and drivers as identified in this study. This paper will assist in the decision making of the various bodies and professions responsible for implementing housing design and provision in developing country contexts, i.e., governmental bodies, policy makers, NGOs, CBOs, planners, architects, engineers and developers. This paper utilized information sources based on many different developing country context worldwide to identify design barriers, challenges and drivers that are common to developing country contexts at large in order to enable design practitioners in developing countries to ensure these aspects are given due consideration in their design decision making process. The author recognizes that many individual developing country contexts, or regions within developing countries, will have individual or region specific factors that will require more in-depth study by designers operating within that context in order to fully establish local design considerations in sufficient specific detail to ensure appropriate design responses for that specific region. As such further research studies on individual developing country contexts by both academics and practitioners of individual countries or regions will enable more region specific detail to be obtained under the various design consideration aspects identified within this paper and add to the knowledge base for designers operating in that specific region or country. Appropriate dissemination of design knowledge gained from

Design Drivers for Affordable and Sustainable Housing in Developing Countries

individual contexts research is essential to ensure that the various potential users identified above have access to the relevant knowledge and guidance and that it is utilized to its full potential in practice.

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International 19 (1) (2005) 73-90. [26] R. Mehta, L. Beidwell, Innovative construction technology for affordable mass housing in Tanzania, East Africa, Construction Management and Economics 23 (2005) 69-79. [27] J. Wells, S.H. Sinda, F. Haddar, Housing and building materials in low-income settlements in Dar es Salaam, Habitat International 22 (4) (1998) 397-409. [28] M.S. Zami, A. Lee, Using Earth as a Building Material for Sustainable Low Cost Housing in Zimbabwe, The Built & Human Environment Review, 2008. [29] P. Tiwari, Sustainable practices to meet shelter needs in India, Journal of Urban Planning and Development 29 (2) (2003) 65-83. [30] D.R. Moore, N. Ahmed, Proposal for the development of an indigenous materials and methods—Oriented design data aid for design professionals practicing in developing nations, Habitat International 21 (1) (1997) 29-49. [31] M.S. Zami, A. Lee, Economic benefits of contemporary earth construction in low-cost urban housing—State-of-the-art review, Journal of Building Appraisal 5 (2010) 259-271. [32] K. Hadjri, M. Osmani, B. Baiche, C. Chifunda, Attitude towards earth building for Zambian housing provision, in: Proceedings of the ICE Institution of Civil Engineers, Engineering Sustainability 160 (2007) 141-149. [33] A.O. Olotuah, Recourse to earth for low-cost housing in Nigeria, Building and Environment 37 (2002) 123-129. [34] D. O’Brien, I. Ahmed, D. Hes, Housing reconstruction in Aceh: Relationships between house type and environmental sustainability, in: Conference Proceedings, Building Abroad—Procurement of Construction and Reconstruction Projects in the International Context, Montreal, Oct. 2008, pp. 361-370. [35] K.J. Charles, U. Paul, Low cost construction technologies and materials—Case study Mozambique, in: Proceedings of the 11th International Conference on Non-conventional Materials and Technologies (NOCMAT 2009), Bath, UK, Sep. 6-9, 2009. [36] B. Hamm, P.K. Muttagi, Sustainable Development and the Future of Cities, Intermediate Technology Publications, London, 1998. [37] R. Lorch, Sustainable development and regionalism, Building Research & Information 33 (5) (2005) 393-396. [38] E. Cromley, Cultural embeddedness in vernacular architecture, Building Research & Information 36 (3) (2008) 301-304. [39] S. Guy, Cultures of architecture and sustainability, Building Research & Information 33 (5) (2005) 468-471. [40] V.O. Cigdem, E. Yalciner, G. Nilufer, Local participatory mechanisms and collective actions for sustainable urban development in Turkey, Habitat International 35 (2011)

9-16. [41] M. Holden, M. Roseland, K. Ferguson, A. Perl, Seeking urban sustainability on the world stage, Habitat International 32 (2008) 305-317. [42] A. Maskrey, Disaster Mitigation: A Community Based Approach, Oxfam, Oxford, 1989. [43] M.B.G. Choguill, A ladder of community participation for underdeveloped countries, Habitat International 20 (3) (1996) 431-444. [44] C. Ebsen, B. Rambol, International review of sustainable low-cost housing projects, in: Proceedings of Strategies for a Sustainable Built Environment, Pretoria, Aug. 23-25, 2000. [45] C. du Plessis, Sustainable development demands dialogue between developed and developing countries, Building Research & Information 27 (6) (1999) 378-379. [46] R.J. Cole, R. Lorch, Buildings, Culture and Environment, Informing Local & Global Practice, Blackwell Publishing, Oxford, 2003. [47] P. Oliver, Technology Transfer—A Vernacular View, in Buildings, Culture and Environment, Informing Local & Global Practice, Blackwell Publishing, Oxford, 2003. [48] M. Vellinga, Sustainable architecture in an age of gentle apocalypse, Building Research & Information 32 (4) (2004) 339-343. [49] H. Frey, P. Yaneske, Visions of Sustainability: Cities and Regions, Taylor & Francis, New York, USA, 2007. [50] J. Gibberd, Building Systems to Support Sustainable Development in Developing Countries, Facilities Planning and Management, CSIR Building and Construction Technology, Pretoria, 2003. [51] J. Gibberd, Assessing sustainable buildings in developing countries—The sustainable building assessment tool (SBAT) and the sustainable building lifecycle (SBL), in: 2005 World Sustainable Building Conference, Tokyo, Sep. 27-29, 2005. [52] H.H. Ali, S.F. Nsairat, Developing a green building assessment tool for developing countries—Case of Jordan, Building and Environment 44 (5) (2009) 1053-1064. [53] Y. Liu, D. Pradad, D. Li, J. Liu, Developing regionally specific environmental building tools for China, Building Research & Information 34 (4) (2006) 372-386. [54] J.A. Todd, S. Geissler, Regional and cultural issues in environmental performance assessment for buildings, Building Research & Information 27 (4-5) (1999) 247-256. [55] E. Kaatz, D. Root, P. Bowen, Broadening project participation through a modified building sustainability assessment, Building Research & Information 33 (5) (2005) 441-454. [56] J. Turner, Tools for building community: An examination of 13 hypthosis, Habitat International 20 (3) (1996) 339-347.

Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1229-1239 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

DAVID

PUBLISHING

Investigation of Bed Joint Reinforcement Influence on Mechanical Properties of Masonry under Compression Lukasz Drobiec Department of Building Structures, Faculty of Civil Engineering, Silesia University of Technology, Gliwice 44-100, Poland Abstract: The results of investigations of compressed reinforced masonry walls subjected to axial compression are presented. Tests were carried out using specimens made of clay bricks and cement-lime mortar. As reinforcement, smooth and spiral twisted longitudinal rods, two types of structural wire mesh and truss type reinforcement were used. Two percentages of bed joint reinforcement, about 0.1% and 0.05% were applied. For each type of reinforcement, three masonry walls were tested. Additionally, nine unreinforced models were also tested. The main aim of the investigations presented is to determine the effect of different types of reinforcement on the load capacity and failure. Measurement of the strains of reinforcing bars permitted the recording of the strain level at the moment of crack appearance and also at the moment of failure. Key words: Reinforced masonry, bed joint reinforcement, compressed masonry.

1. Introduction Reinforcement has been used in masonry structures for about the last 200 years. Bed joint reinforcement is usually used for in-plane bending elements (like masonry lintels, walls affected by considerable deflections of floors) [1-7]. Moreover, it could be used in places of stress concentration (corners of window opening) [1, 4-8] and in wall areas under concentrated loads [6]. Of course, reinforcement is also used in elements endangered by shrinkage or thermal stresses [1, 8], or a horizontal load (wind load) [5]. In building practice, bed joint reinforcement is also used in buildings with timber floors where it takes over the stress irregularity from the rim under the wall plate [1, 4-6, 9]. Moreover, bed joint reinforcement is also used for reducing of scratching [4, 10-11] protecting against seismic and paraseismic influences [7] and for improvement of masonry mechanical properties [11]. All the above cases of bed joint reinforcement application show that it is usually used in elements loaded mostly vertically. Unfortunately, the research Corresponding author: Drobiec Lukasz, Ph.D., C.Eng., research fields: concrete structures and masonry structures. E-mail: lukasz.drobiec@polsl.pl.

into compressed masonry with the reinforcement situated in the bed joints comprises only a few levels of reinforcement percentage. Most investigations concern unreinforced masonry specimens under compression. Tests of vertically compressed reinforced masonry wallettes are presented. Four types of reinforcement in the form of longitudinal bars and structural wire mesh were used. The influence of such types of reinforcement on the load capacity, deformability and crack resistance was determined. Among other things, the influence of longitudinal bars as opposed to wire mesh on the failure form was observed. Measurement of the strain of the reinforcing bars permitted the measurement of the strain level at the moment of crack appearance and also at the moment of failure.

2. Test Models Investigations were carried out using test specimens with overall dimensions of 1,265 mm  1,030 mm  250 mm shown in Fig. 1. All elements were built of clay bricks (with dimensions 65 mm  120 mm  250 mm) and cement-lime mortars 1:1:6 (portland cement:lime:sand). The depth of mortar joints in masonry models was 10 mm. Tests included 9 sets of

Investigation of Bed Joint Reinforcement Influence on Mechanical Properties of Masonry under Compression

1230

where the reinforcement percentage is 0.1%). As reinforcement in FI and FII series were used truss made from two longitudinal bars 5 mm in diameter and welded continuous wire diagonal (4.5 mm). In FI series reinforcement was placed in every 6th bed joint (the reinforcement percentage was about 0.05%), while in FII series in every 3rd bed joint (the reinforcement percentage was about 0.1%). To ensure sufficient anchorage, flat bars 6 mm  20 mm  40 mm were welded on the ends of longitudinal rods, and flat bars 6

Fig. 1

Test specimen.

the unreinforced masonry specimens marked as “A” and 24 specimens with 4 types of reinforcement. Two reinforcement percentages: about 0.1% and about 0.05% were used. The first type of reinforcement was smooth stainless steel bars with a diameter of 6 mm. The second was spiral twisted bars of one of the British systems for protection and strengthening of masonry fractures, with an outer diameter of about 6 mm. The series of specimens with smooth bars was marked as “B” (BI—the reinforcement percentage about 0.05% and BII with reinforcement percentage 0.1%). Reinforced series built with using of spiral bars were marked as “C” (CI and CII). Additionally, two types of wire mesh, stainless woven wire mesh with bars of diameter 4 mm (spacing between bars 40 mm  40 mm) and welded wire mesh from zinc coated steel with the bars of diameter 1.25 mm and spacing in both directions 12 mm  12 mm were used. A series of specimens with wire mesh with 4 mm diameter of bars was marked as “D” (DI where the reinforcement percentage is 0.05% and DII where the reinforcement percentage is 0.1%). Test wallettes with mesh with 1.25 mm diameter welded bars were marked as “E” (EI where the reinforcement percentage is 0.05% and EII

mm  20 mm  220 mm on the wire mesh ends. All specimens were loaded during the investigations in a single cycle. Readings of load level and other measurements were made every 150 kN. For load force measurement, a dynamometer was used and for displacement reading inductive sensors with an accuracy of 0.002 mm were used. In specimens in the “B”, “C” and “D” series, the measurement of rod deformation was made using foil strain gauges—one gauge in the middle of the length of each steel bar. Unfortunately, by reason of the bars’ small diameter in models of the “E” series, it was impossible to use foil gauges for deformation measurement. Therefore, for these specimens the steel strains were not measured. A general view of the test wallette and the inductive sensor placing is given in Fig. 1. All types of reinforcement with the strain gauge distribution is shown in Fig. 2. Simultaneously, material tests of compressive and tensile strength of the mortar according to EN 1015 [12] regulations were carried out. The compressive strength and modulus of elasticity of bricks to EN 772-1 [13] were also measured. The tensile strength of reinforcing steel according to Polish Standard PN-91/H-04310 [14] was measured. Additionally, using EN 1052-1 [15] the compressive strength and modulus of elasticity of masonry specimens were tested.

3. Results of Material Properties Tests The values of the mortar properties and compressive strength of bricks are shown in Table 1. The compressive

In nvestigation of Bed Joint Reinforceme ent Influence on Mechanic cal asonry under Compressio on Properties of Ma

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Fig. 2 Type of models rein nforcement. Table 1

Mortar and clay bricks b propertties. Clayy bricks EN 772 2-1 [13]

M Mortar EN 1015 5 [12]

Determined value

Compressive strength fm (N/m mm2) 2 Bending strenngth fmt (N/mm )

Value 7.2 2.4

strength of the mortar was w 7.2 N/m mm2, whereass the tensile strenngth in bendinng was aboutt 2.4 N/mm2. The compressivee strength of bricks b was abbout 69.7 N/m mm2. In Table 2, the t values off ultimate tensile force, tennsile strength, yieeld point and modulus m of elasticity obtaained for smooth and spiral twisted t rods are given. The reinforcing bars b strength-strain graph was acquiredd by using extenssometer. The load capacityy of masonry tests t

 (% %) 6.6 5.5

Value 69.7 -

 (% %) 3.8 -

according to EN N 1052-1 [115] were con nducted. Thee mecchanical propperties of thee masonry ob btained in thee testts are shown in i Table 3.

4. Results R of Main M Invesstigations In n Table 4, thhe comparisonn of the averaage values off com mpressive strrength, moddulus of elasticity E andd Poisson’s ratio for all unreeinforced and reinforcedd

In nvestigation of Bed Joint Reinforceme ent Influence on Mechanic cal asonry under Compressio on Properties of Ma

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Table 2

Smoooth and spiraal rod properties. 04310 [14] Spiral rod PN-91/H-0

Smoothh rod PN-91/H--04310 [14] Determined value

Rip force (kN N) Tensile strenggth (N/mm2) Yield point (N N/mm2) Modulus of ellasticity (N/mm m2)

Value 23.1 817 760 204,000

 (% %) 0.9 0.9 0.7 1.2

Value 8.4 970 910 -

 (% %) 0.8 0.8 0.7 -

Table 3 Massonry propertiies. Masonry specim men EN 1052-11 [15]

Determined value

Compressive stress (N/mm ) Modulus of ellasticity (N/mm m2) Poisson’s ratioo Table 4

 (%) 6.9 9.4 6.8

value 15.4 12,135 0.23

Com mpressive stren ngth, moduluss of elasticity and Poisson’s ratio for all testt series.

Determined value series symbol A BI BII CI CII DI DII EI EII FI FII

o steel Kind of Smootth bars Smootth bars Spiral twisted bars Spiral twisted bars Wovenn wire mesh Wovenn wire mesh Weldeed wire mesh Weldeed wire mesh Truss type t Truss type t

Percentage off armature (%) About 0.05 About 0.1 About 0.05* About 0.1* About 0.05 About 0.1 About 0.05 About 0.1 About 0.05 About 0.1

Comprressive strengtth (N/mm2) 14.08 16.22 13.98 15.13 13.26 17.30 17.53 19.22 19.83 14.3 17.6

Modulus of elasticity (N/mm2) 13,910 14,440 14,600 12,250 13,260 12,470 12,180 12,420 13,640 10,779 11,830

n’s ratio Poisson 0.21 0.20 0.23 0.13 0.15 0.15 0.15 0.13 0.13 0.18 0.16

*Percentage of reinforcementt after outside diameter. d

masonry waallettes is show wn. The com mpressive strenngth of unreinforcced specimenns is about 14.08 N/mm2 annd is about 10% % lower thaan obtained from standard specimens according a to Ref. R [15], as shown s in Tabble 3. The compparison of thhe resultant stress-strain s ( (σ-ε) relationshipss for all unreeinforced models (“A” serries)

and d masonry speecimens (accoording to the standard s [15]]) is shown s in Figg. 3. The initial part of bo oth curves iss quitte similar. The ultimate (maximum m) value off com mpressive strress is greateer for the sm maller (EC-66 Stan ndard) specim mens. The tanngent angle of o inclinationn with h regard to thhe σ-ε curve for models of o “A” seriess

Investigation of Bed Joint Reinforcement Influence on Mechanical Properties of Masonry under Compression

1233

decreases more quickly than for the standards’ specimens, where it is nearly stable up to about 85% of ultimate compressive strength. The graphs of average values of σ-ε relationships for all test series are shown in Fig. 4.

increase of strength was only a small percentage for

5. Analysis

decrease of strength was obtained for spiral twisted bar

models of BI and CI series, about 15% and 7.5%, respectively. However, in models of BII and CII series (bigger percentage of reinforcement) some decrease of compressive strength was observed. A more significant reinforced models (CII). The decrease of the

5.1 Models with Longitudinal Bed Joint Reinforcement

compressive strength of the more strongly reinforced

The comparison of the compressive strength values

elements (ρ = 0.1%) is connected with a change in the

of reinforced wallettes with longitudinal bars with

form of their failure. In unreinforced models, first

unreinforced specimens (Table 4) shows that the

cracks appeared at about 40-50% of the maximum

18.0 16.0

σ (N/mm2)

14.0 12.0 10.0 8.0 6.0 4.0 2.0 0 0.0000

0.0005

0.0010

0.0015

0.0020

0.0025

0.0030

0.0035

Fig. 3 The σ-ε relationship for unreinforced models: “A” series and EC-6 masonry standards’ specimens. 25.0 20.0

σ (N/mm2)

15.0

10.0 5.0 0.0

0.0000 0.0005

0.0010

0.0015

0.0020

Fig. 4 Graphs of average σ-ε relationships for all test series.

0.0025

0.0030 0.0035

0.0040

0.0045

1234

Investigation of Bed Joint Reinforcement Influence on Mechanical Properties of Masonry under Compression

compressive stress. All cracks had a generally vertical direction. In agreement with Hilsdorf theory, the masonry units cracked first. Then, as the load increased the cracks included head joints of the upper and lower neighbouring brick courses and as a consequence, the wallette divided into a few separate pillars (Fig. 5a). Failure of specimens with longitudinal reinforcement was quite different. All models were split into two separate leaves by an internal crack (as shown in Fig. 5b). The decrease of strength, which is greater for reinforced specimens with the smooth bars, is related to the appearance of the notch effect, which is connected with a stiff inclusion, in shape of bars, in weak mortar joints. All elements with the smaller percentage of reinforcement (BI and CI series) were characterized by a larger number of cracks, which also had a larger width than observed in models of BII and CII series. In models of BII series (ρ = 0.1%) the local spalling of the masonry surface in the area of bars’ location was observed. Some graphs displaying an average stress range (from the first crack appearance to failure) is presented in Fig. 6. Elements reinforced with the spiral bars cracked under greater stress levels than elements reinforced with smooth steel rods. Cracking of models reinforced with spiral bars took place with almost the

same stress level as for unreinforced models. The stress level corresponding with crack appearance of reinforced models was lower than obtained for unreinforced specimens. The first crack in reinforced (using longitudinal bars) models always appeared in a different place to that in the unreinforced elements. Graphs of steel deformation in relation to compressive strength level in the wallettes are presented in Fig. 7. The first to strain were the spiral rods (larger adherence of to mortar in joint). The rods in masonry with a greater percentage of reinforcement (ρ = 0.1%) stretched earlier. The comparison of the strength of tensile rods located in the masonry with σt-ε relationship obtained from the smooth rod tensile tests are shown in Fig. 8. For smooth rods in the wall with a percentage about 0.05% (BI series), the level of tensile stress of 53% of the yield point of steel were obtained. Whereas for smooth bars in masonry with double that percentage (about 0.1% in BII series), the level of tensile stress was about 39% of the yield point of steel. The designated level of tensile stress in spiral bars was 49% of the yield point of steel for models of CI series and 30% for CII series. The comparison of both types of bed joint reinforcement shows that spiral bars are more effective. That kind of reinforcement combined better with the mortar in the walls’ joints (Fig. 7) and

(a) (b) Fig. 5 Typical crack pattern of tested elements: (a) unreinforced and with wire mesh reinforcement; (b) reinforced with longitudinal bars and truss type.

σ (N/mm2)

Investigation of Bed Joint Reinforcement Influence on Mechanical Properties of Masonry under Compression

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24.0 22.0 20.0 18.0 16.0 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0

σt (N/mm2)

Fig. 6 Graph of stress interval from first crack to failure for all test series. 22.0 20.0 18.0 16.0 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 0

ρ = 0.05%

ρ = 0.05% ρ = 0.1% ρ = 0.1%

0.0005

0.001

0.0015

0.002

0.0025

0.003

σt (N/mm2)

Fig. 7 Graph of steel deformation in relation to compressive stress level for “B” and “C” series.

ρ = 0.05% ρ = 0.1%

0‰ 5‰ 10‰

Fig. 8

15‰

Comparison of σt-ε relationships for rods located in masonry with σt-ε obtained from rod tensile tests.

Investigation of Bed Joint Reinforcement Influence on Mechanical Properties of Masonry under Compression

1236

did not change the value of modulus of elasticity in comparison to the unreinforced models (Table 4). Moreover, it has much better influence on the crack resistance (Fig. 6). The increase of strength obtained for models with the lower reinforcement percentage (CI) towards the elements reinforced with smooth steel (BI) could be explained by its three times lower area than the spiral bars. As in case of reinforcement in the shape of smooth bar (BII), there was found to be some decreasing of load capacity for series with greater (ρ = 0.1%) reinforced percentage (CII). 5.2 Models with Wire Mesh Reinforcement Reinforcement in the shape of wire mesh gives a more significant growth of load capacity in comparison to reinforcement in the form of longitudinal bars (Table 4). In the case of the lower reinforcement percentage, the growth of the load capacity for woven wire mesh reinforcement (DI) was about 23% and for welded wire mesh (EI) about 37%. Doubling the reinforcement percentage caused a slight growth of load capacity. For walls reinforced with the greater percentage of woven wire mesh (DII), the authors obtained a growth of the load capacity of over 25% in comparison to the unreinforced models. For specimens with welded wire mesh (EII), the load capacity increased even more by about 41%. The failure shape of tested wallettes was

typical—all specimens were divided by vertical cracks into a few pillars. It is an identical situation to that observed for unreinforced models (Fig. 5a). Using a wire mesh bed joint reinforcement eliminated the disadvantageous crack pattern which was observed for elements with longitudinal bar reinforcement. In the models of “D” series, the failure was connected with the reinforcement anchorage and vertical cracks in the anchorage planes. In elements of “E” series, the failure by a few vertical cracks corresponded with the moment of breaking the reinforcement (two longitudinal bars). The wire mesh worked with the masonry much better than longitudinal bars because the mesh limited the mortar’s deformation in the whole horizontal plane. The deformation of longitudinal and lateral bars in the “DI” models as a function of compressive stress is shown in Fig. 9. It shows that longitudinal and lateral bars worked in a similar way. That is why the influence of the wire mesh longitudinal bars is very important for masonry strength. The comparison of the deformation of the longitudinal bars of the “B” and “C” series with wire mesh longitudinal 4 mm diameter bars (Fig. 9) shows that the deformation of wire mesh bars is less by half. Reinforcement in the form of wire mesh also has a greater influence on masonry crack resistance. The limitation of mortar deformation has a significant

20.0 18.0 16.0 14.0

σ (N/mm2)

12.0 10.0 8.0 6.0 4.0 2.0 0.0

0.0002

0.0004

0.0006 0.0008

0.001

0.0012

0.0014

0.0016

Fig. 9 Steel deformations for lateral and longitudinal bars in relation to compressive stress for models of “D” series.

Investigation of Bed Joint Reinforcement Influence on Mechanical Properties of Masonry under Compression

influence on the level of stress corresponding with the first crack appearance (Fig. 6). In the case of the “D” series, first cracks were observed for a compressive stress level σc of about 13 N/mm2, whereas the elements of the “E” series were cracked at σc of about 14.3 N/mm2, a result similar to the unreinforced elements. 5.3 Models with Truss Type Reinforcement The comparison of values of the compressive strength of unreinforced and reinforced F series (Table 4) was found that small percentage of the reinforcement in FI specimens does not have an effort on carrying capacity of masonry and the bigger percentage (FII specimens) increases about 25% of the strength. Reinforcement reduces masonry modulus of elasticity and Poisson’s ratio. Bed joint reinforcement caused the change of

Fig. 10

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masonry failure. Destruction was always into internal joint. All models were split into two independent shields (Fig. 10). There were cut out the reinforcements from every specimens after finishing the researches. It was said that the tensile failure was done to the continuous wire diagonal (Fig. 11), what explains the cracks along the internal joint. The results of the measurement of the strains of reinforcing bars with both percentages showed that the strains of the longitudinal bars and the continuous wire diagonal are similar. The tensile failure of the continuous wire diagonal results from the smaller diameter. It is clear that using the continuous wire diagonal with the higher diameter may cause the increase the crack resistance and compressive strength of masonry. Fig. 12 are displayed exemplary reinforcement strains in the function of masonry compressive strength.

Failure of FI series models.

Fig. 11 Truss type reinforcement cut out from specimen after finishing the researches.

Investigation of Bed Joint Reinforcement Influence on Mechanical Properties of Masonry under Compression

1238

16.0 14.0

σt (N/mm2)

12.0 10.0 8.0 6.0 4.0 2.0 0.0 0

Fig. 12

0.0002

0.0004 0.0006

0.0008 0.001 0.0012 0.0014 0.0016 0.0018 0.002

Bars steel deformations in relation to compressive stress for models of “F” series.

6. Conclusions The investigations carried out showed the significant influence of bed joint reinforcement on the behavior of masonry wallettes subjected to axial compressive loads. The analysis of tests results given above leads the authors to formulate the following conclusions: (1) Using bed joint reinforcement in the shape of longitudinal bars (smooth and spiral twisted) is not very beneficial. For ρ = 0.05% a slight growth of load capacity in comparison with unreinforced specimens was determined. Unfortunately, for double the ρ value (ρ = 0.1%) a decrease of the load capacity was noted; (2) A very disadvantageous failure shape (dividing of the wall into two separate leaves) was observed for specimens reinforced with longitudinal bars and truss type; (3) A more positive effect is given by the use of woven or welded wire mesh bed joint reinforcement. For reinforcement percentage ρ = 0.05%, about 23% (woven wire mesh) and about 37% (welded wire mesh) growth of load capacity with reference to unreinforced specimens was obtained. Increasing of ρ value (up to ρ = 0.1%) gave a further slight growth of load capacity;

of the capacity (about 25%) and crack resistance (about 23%); (6) The usage of reinforcement has influence on the failure of models: limited scratching of front surfaces of elements and destruction in internal joint.

References [1]

[2]

[3]

[4]

[5]

[6]

(4) The failure shape was typically the same as in the case of unreinforced specimens—dividing the masonry wallettes by vertical cracks into a few separate pillars; (5) In models with truss type reinforcement small reinforcement percentage (ρ = 0.05%) did not effect the mechanical features of the masonry. Double increase of the reinforcement (ρ = 0.1%) caused the enlargement

[7] [8]

[9]

K.J. Schneider, N. Weickenmeier, Present Masonry Constructions, Werner Verlag GmBH & Co.KG, Düsseldorf, Berlin, 2000. J.E. Amrhein, Reinforced Masonry Engineering Handbook, Clay and Concrete Masonry, Masonry Institute of America, CRC Press Boca Raton, New York, 1998. L. Drobiec, About the necessity of using appropriate reinforcement in the wall bed joint, Monography Reprocity Resume, Faculty of Civil Engineering, Silesian University of Technology, Gliwice, 2008, pp. 89-95. P. Timperman, J.A. Rice, Bed joint reinforcement in masonry, in: Proceedings of the Fourth International Masonry Conference, British Masonry Society, London, 1995, pp. 451-453. O. Pfeffermann, G. van de Loock, 20 Years experience with bed joint reinforced masonry in Belgium and Europe, in: Proceedings of the 9th International Brick/Block Masonry Conference, Berlin, Germany, 1991, pp. 427-436. P. Schiessl, S. Schmidt, Reinforced masonry—Discussion about the way of building, Beratende Ingenieure 7 (8) (1989) 28-31. (in German) G. van de Loock, Special reinforcement of masonry, Ziegelindustrie International 1 (1980) 16-18. (in German) T. Mader, Reinforced masonry in practice bewehrtes mauerwerk in der praxis, Das Bauzentrum 5 (1993) 65-66. (in German) W. Jäger, L. Drobiec, Bed joint reinforced masonry under vertical compression, Mauerwerk 6 (2006) 252-257. (in

Investigation of Bed Joint Reinforcement Influence on Mechanical Properties of Masonry under Compression German) [10] R. Pohl, The reinforcement increases the way of using the brick walls, Das Bauzentrum 9 (1996) 125-128. (in German) [11] O. Pfeffermann, B. van Hoorickx, Some practicular applications of reinforced masonry in Belgium, in: Proceedings of the 12th International Brick/Block Masonry Conference, Madrid, Spain, 2000, pp. 1437-1446.

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[12] BS EN 1015-11:1999, EN 1015 Methods of Test for Mortar for Masonry, British Standards Institution, 1999. [13] EN 772-1 Methods of Test for Masonry Unitsâ&#x20AC;&#x201D;Part 1: Determination of Compressive Strength, 2000. [14] PN-91/H-04310, Static Tensile Testing of Metals, Polish Code, 1991. (in Polish) [15] EN 1052-1 Method of Test for Masonry, Determination of Compressive Strength, Brussels, Belgium, 1999.

Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1240-1252 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

DAVID

PUBLISHING

Evaluating the Effectiveness of Best Management Practices in Gilgel Gibe Basin Watershedâ&#x20AC;&#x201D;Ethiopia Tamene Adugna Demissie1, Fokke Saathoff2, Yilma Seleshi3 and Alemayehu Gebissa2 1. Department of Civil Engineering, Jimma Institute of Tehnology, Jimma University, Jimma 378, Ethiopia 2. Institute for Environmental Engineering, University of Rostock, Rostock 18051, Germany 3. Civil Engineering Department, Addis Ababa Institute of Technology, Addis Ababa University, Addis Ababa 150461, Ethiopia Abstract: Soil erosion/sedimentation is an immense problem threatening the live storage capacity of dam reservoirs in Ethiopia. This in turn reduces the power generation capacities of hydropower reservoirs. Therefore, studies which give insight into soil erosion/sedimentation mechanisms and mitigation methods is important. The high rate of soil erosion/sedimentation threats the lifespan of Gilgel Gibe-1 hydropower reservoir. The problem of sedimentation in Gilgel Gibe-1 will also affect Gilgel Gibe-2 which uses the water released from Gilgel Gibe-1. The sustainability of these hydropower plants needs catchment management practices that will reduce soil erosion. This paper presents the results of monthly and yearly sediment yield simulations experiments conducted for Gilgel Gibe-1 under different BMP (best management practice) scenarios. The scenarios applied in this paper are: (1) maintaining existing conditions; (2) introducing filter strips; (3) applying stone/soil bunds; (4) reforestation. The SWAT (soil and water assessment tool) was used to model soil erosion, identify soil erosion prone areas and assess the impact of BMPs on sediment reduction via simulations. The simulation results showed that applying filter strips, stone bunds and reforestation scenarios could reduce the current sediment yields at soil erosion prone areas and at the outlet of the catchment area which is the inlet to Gilgel Gibe-1 reservoir. Key words: BMPs, SWAT, sedimentation.

1. Introductionď&#x20AC; The Gilgel Gibe River is a right hand tributary of one of the eight major river basins in Ethiopia, the Omo-Gibe river basin. It is the major source of water for Gilgel Gibe dam reservoir project which has a live storage capacity of 657 Mm3. But the storage volume of this reservoir is threatened by the soil erosion and subsequent sedimentation from the upstream of the Gilgel Gibe basin. Previous studies indicate that there is a rapid loss of storage volume due to excessive soil erosion and subsequent sedimentation in Gilgel Gibe-1 dam reservoir. Devi et al. [1] conducted a cross sectional study and assessed the siltation and nutrient enrichment level of Gilgel Gibe-1 dam reservoir. From their study, they found that siltation Corresponding author: Tamene Adugna Demissie, M.Sc., research fields: water resources management and watershed modeling. E-mail: tamene_adu2002@yahoo.com.

and nutrient enrichment were the major problems in this reservoir. In addition to Gilgel Gibe-1 hydropower plant, the power generation of the Cascade hydropower plant to Gilgel Gibe-1, namely Gilgel Gibe-2 Which has an installed capacity of 420 MW and uses the water released from the same reservoir, will significantly be affected. Currently, the government of Ethiopia is constructing a huge hydropower plant, Gilgel Gibe-3, downstream of Gilgel Gibe-1 and 2. The Gilgel Gibe-3 dam and powerhouse are being built approximately 155 km downstream of the Gilgel Gibe-2 plant. Up on its completion Gilgel Gibe-3 will have an installed capacity of 1,870 MW. There is also a plan to construct Gilgel Gibe-4 which will be the farthest downstream in the cascade. Though the Government of Ethiopia is putting an effort to

Evaluating the Effectiveness of Best Management Practices in Gilgel Gibe Basin Watershed—Ethiopia

construct large hydropower plants to supply the energy demand of the country, the rapid loss of storage volume due to sedimentation is major problem of all reservoirs. Some preliminary studies indicate that the levels of some reservoirs (e.g., Koka reservoir), lakes (e.g., Alemaya, Awassa, Abaya and Langano) have decreased. The process is so challenging that the initial water carrying capacity the dams has reduced due to progressive silt accumulation. For example, the Koka dam has accumulated about 3.5 million m3 of silt (or 2,300 t·km-2) in just 23 years [2]. Thus, an insight into the soil erosion/sedimentation mechanisms and the mitigation measures plays an indispensable role for the sustainability of the existing reservoirs and newly planned projects. To develop effective soil erosion control mechanisms through watershed development programs and to achieve reductions in sedimentation, it is necessary to quantify the sediment yield and identify areas that are highly vulnerable to erosion. Literature review shows that there are many catchment models that include the soil erosion/sedimentation processes and simulate the effect of mitigation measures [3, 4]. The range of models can be viewed in the way they represent the area to which they are applied, that is, whether the model considers processes and parameters to be lumped or distribute. With increasing computing power over the last two decades, distributed approaches have become more feasible. Distributed models reflect the spatial variability of processes and outputs in the catchment analysis. A distributed approach seems particularly applicable to sediment transport modelling [4]. Some of the soil erosion models are AGNPS (agricultural non-point source pollution model) [5], ANSWERS (areal nonpoint source watershed environmental response simulation) [6], CREAMS (chemicals, runoff and erosion from agricultural management systems) [7], EPIC (erosion productivity impact calculator) [8], EROSION-3D [9], EUROSEM (European soil erosion model) [10],

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SWAT (soil and water assessment tool) [11], WEPP (water erosion prediction project) [12], and so on. However, there are a few applications of erosion modelling in Ethiopia and most of them concentrate on Blue Nile basin. In the Blue Nile Basin [13] simulated soil loss in the Dembecha catchment using WEPP, Haregeweyn and Yohannes [14] applied AGNPS and predicted sediment yield in Augucho catchment. The same AGNPS model was used by Ref. [15] to simulate sediment yield in the kori catchment. Hengsdijk et al. [16] applied LISEM (limburg soil erosion model) to simulate effect of reforestation on soil erosion in the Kushet—Gobo Deguat catchment. Steenhuis et al. [17] calibrated and validated a simple soil erosion model in the Abbay (Upper Blue Nile) basin and obtained a reasonable result, and Setegn et al. [18] applied SWAT for simulation of a sediment yield in the Anjeni gauged catchment and obtained quite acceptable result. SWAT has been successfully applied by different researchers in Ethiopia. Most of the SWAT model applications in Ethiopia concentrate on the Blue Nile river basin. For instance, Tesfahunegn et al. [19] applied SWAT model to evaluate the effectiveness of different scenarios in reducing runoff, sediment and soil nutrient losses in northern Ethiopia. Asres and Awulachew [20] applied the SWAT model to establish the spatial distribution of sediment yield and to test the potential of watershed management measures to reduce sediment loading from hot spot areas in Gumara watershed (Blue Nile) and Betrie et al. [21] also applied the SWAT model to assess the impact of BMPs on sediment reductions in the Upper Blue Nile River Basin. Though the SWAT model is widely applied in Ethiopia, particularly on the Blue Nile river basin, there is no literature that indicates the SWAT model application on Omo-Gibe basin in general and Gilgel Gibe-1 basin in particular. In this study, the SWAT model has been applied to the Gilgel Gibe river basin with specific focus on BMPs application. Currently, there is a recommendation to protect the buffer zone around Gilgel Gibe-1 dam

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Evaluating the Effectiveness of Best Management Practices in Gilgel Gibe Basin Watershedâ&#x20AC;&#x201D;Ethiopia

reservoir from agricultural practices. In addition to the buffer zone protection, the Oromiya Environmental Protection Bureau is also implementing watershed development through the community based participatory approach of Ref. [22] management practices to reduce soil erosion and conserve soil and water under its basin development programme. Such basin development programme should be aided by powerful modelling tools such as SWAT. Therefore, the objective of this study is to model the spatially distributed soil erosion/sedimentation process in the Gilgel Gibe basin at monthly and yearly time steps and assess the impact of different catchment management interventions applied on hot spot areas on sediment yield. A brief description of the Gilgel Gibe basin is given in the next section, followed by a discussion on the methodology used. The third section presents the model results and discussion of different land management scenarios. Finally, the conclusion summarizes the main findings of the investigations.

2. Description of the Study Area As it is indicated in Fig. 1, the Gilgel Gibe-1

Fig. 1

Location map of the Gilgel Gibe-1 watershed.

watershed is situated in the south-western part of Ethiopia. The project is purely a hydropower scheme, with an installed capacity of 180 Mw, aimed to increase energy and power supply to the national grid. The reservoir has a live storage capacity of 657 mm3. The catchment area of the Gilgel Gibe basin is about 5,125 km2 at its confluence with the great Gibe River and about 4,225 km2 at the dam site. The basin is generally characterized by high relief hills and mountains with an average elevation of about 1,700 m above mean sea level. The basin is largely comprises of cultivated land. In general terms, the Gilgel Gibe basin is characterized by wet climate with an average annual rainfall of about 1,550 mm and average temperature of 19 oC. The seasonal rainfall distribution takes a uni-modal pattern with maximum during summer and minimum during winter, influenced by the ITCZ (inter-tropical convergence zone).

3. Methodology 3.1 SWAT Model Description The SWAT is a physical process based model to

Evaluating the Effectiveness of Best Management Practices in Gilgel Gibe Basin Watershedâ&#x20AC;&#x201D;Ethiopia

simulate continuous time landscape processes at a catchment scale [11, 21, 23]. The catchment is divided into HRU (hydrological response units) based on soil type, land use and slope classes. The major model components include hydrology, weather, soil erosion, nutrients, soil temperature, crop growth, pesticides agricultural management and stream routing. The model predicts the hydrology at each HRU using the water balance equation, which includes daily precipitation, runoff, evapo-transpiration, and percolation and return flow components. The SWAT model has two options for computing surface runoff: (1) the Natural Resources Conservation Service CN (Curve Number) method [24]; or (2) the Green-Ampt method [25]. The flow routing in the river channels is computed using the variable storage coefficient method [26], or Muskingum method [27]. SWAT includes three methods for estimating potential evapo-transpiration: (1) Priestley-Taylor [28]; (2) Penman-Monteith [29]; (3) Hargreaves [30]. The SWAT model employs the MUSLE (modified universal equations) to compute HRUs level soil erosion. It uses runoff energy to detach and transport sediment [31]. The sediment routing in the channel [32] consists of channel degradation using stream power [33] and deposition in channel using fall velocity. Channel degradation adjusted using USLE soil erodibility and channel cover factors. 3.2 SWAT Model Setup SWAT model inputs are DEM (digital elevation model), land use map, soil map and weather data. There is a considerable amount of data available on the web, and Map Window SWAT used in this study used this advantage. MWSWAT (Map Window SWAT) is delivered along with the following data [34]: DEM maps: SRTM project [35]; Land: Global Land Cover characterization [36]; Soil maps: FAO (Food and Agricultural Organization) [37]. The Step by Step Geo-Processing & Set up of the Map window interface for SWAT (MWSWAT) documents [38, 39],

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have been followed to extract the required watershed data and to set up the SWAT model for Gilgel Gibe basin. The DEM was used to delineate the catchment and provide topographic parameters such as overland slope and slope length for each sub-basin. The catchment area of the Gilgel Gibe was delineated and discretized into 51 sub-basins using a 90 m DEM [40] through an MWSWAT interface. The Land use data which has been constructed from the USGS Global Land Cover Characterization (GLCC) database [41], by Abbaspour is used. This map has a spatial resolution of 1 km and 24 classes of land use representation. The parameterization of the land use classes (e.g., leaf area index, maximum stomatal conductance, and maximum root depth, optimal and minimum temperature for plant growth) is based on the available SWAT land use classes. The land cover classes derived are CRDY (dry land Cropland and pasture), 36.68%, Gras (Grassland), 15.56%, SAVA (Savanna) 14.45%, FOEB (evergreen forest) 22.65%, FOMI (mixed forest) 9.92% and CRWO (Cropland/woodland mosaic), 0.74%. The soil map was produced by the Food and Agriculture Organization of the United Nations [42]. Almost 5,000 soil types at a spatial resolution of 10 km with soil properties for two layers (0-30) cm and 30-100 cm depth) are provided. Further soil properties (e.g., particle-size distribution, bulk density, organic carbon content, available water capacity, and saturated hydraulic conductivity) were obtained from Ref. [43]. The soil data is also available from the Water Base web site [44], and was extracted for the study area. FAO soil and the slope class maps were overlaid together to derive 410 unique HRUs. Although the SWAT model provides an option to reduce the number of HRUs in order to enhance the computation time required for the simulation, we considered all of the HRUs with land use of dry land, cropland and pasture of to evaluate the management intervention impact. The daily precipitation, maximum and minimum temperature, wind speed, average relative

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Evaluating the Effectiveness of Best Management Practices in Gilgel Gibe Basin Watershed—Ethiopia

humidity data from Jimma and Sekoru stations were used to run the model. In addition, as Jimma and Sekoru meteorological stations have daily data on duration of sunshine hours, the Angstrom formula which relates solar radiation to extraterrestrial radiation and relative sunshine duration is used to estimate the daily solar radiation to be used in the model. The missed sunshine data were filled by non-linear regression analysis with other auxiliary climate variables such as relative humidity and temperature data before it was used to estimate solar radiation. The solar radiation data is required by SWAT and if not supplied SWAT generates this data. Though all the daily weather data which are required to run the model have been supplied, the weather generator file was also prepared using the 20 years daily data from these two stations and included in the project file. Daily river flow data measured at Asendabo gauging station was used for model calibration and validation. The flow observations were available throughout the year, but the sediment concentration data was not available for Gilgel Gibe basin. The model was run using daily data of 26 years. The daily meteorological data from 1980 to 2005 was used to run the model. The three years data from 1980 to 1982 was used to warm up the model. Whereas, the data from 1983 to 1992 was used to calibrate the model and the data from 1993 to 2000 was used to validate the model. The modeling period selection considered discharge data quality and availability. A daily flow was used to calibrate and validate the model at Asendabo gauging station and sediment discharge was simulated at the outlet of the Gilgel Gibe watershed which is in turn an inlet to the Gilgel Gibe-1 hydropower reservoir. Sensitivity analysis was carried out to identify the most sensitive parameters for model calibration using LH-OAT (One-factor-At-a-Time), an automatic sensitivity analysis tool implemented in SWAT 2005. SWAT 2005 editor is used to read the project database generated by Map Window SWAT interface to edit

SWAT input files, execute SWAT, and perform sensitivity, auto calibration and uncertainty analysis. Based on the sensitivity analysis results, we identified 8 parameters of interest for this basin. We started with all 27 hydrological flow related parameters and ranked by their order of sensitivity in simulating the basin hydrology. It resulted in about 8 parameters as the most sensitive ones for this basin. Followed by the sensitivity analysis, the most sensitive parameters were calibrated by both manual calibration (expert) and automatic calibration. Appropriate lower and upper ranges in parameter values have been assigned prior to initiating the auto calibration process. 3.3 Model Performance Evaluation Model evaluation is an essential measure to verify the robustness of the model. In this study, the following

methods

were

used:

(1)

NSE

(Nash-Sutcliffe efficiency); (2) PBIAS (percent bias); (3) correlation between observed and simulated flows. The NSE (Nash-Sutcliffe efficiency) is computed as the ratio of residual variance to measured data variances [45]. The NSE simulation coefficient indicates how well the plot of observed versus simulated values fits the 1:1 line. The Nash-Sutcliffe is calculated using Eq. (1):

 n obs sim 2   (Q i  Q i ) NSE  1   ni  1  ( Q iobs  Q mean ) 2   i 1

    

(1)

where,

Qiobs  observed stream flow in m3/s;

Qisim  simulated stream flow in m3/s;

Q mean  mean of n values; sim Qmean  mean of simulated values; obs Qmean  mean of observed values; n =number of observations. The NSE can range from   to +1, with 1 being

a perfect agreement between the model and real (observed) data. The simulation results were

Evaluating the Effectiveness of Best Management Practices in Gilgel Gibe Basin Watershed—Ethiopia

considered to be good if NSE ≥ 0.75, and satisfactory if 0.36 ≤ NSE ≤ 0.75 [46]. The PBIAS (percent bias) measure the average tendency of the simulated data to be larger or smaller than their observed counterparts. A positive value indicates a model bias toward underestimation, whereas a negative value indicates a bias toward overestimation [47]. The PBIAS < ±25% is satisfactory [48]. The PBIAS is calculated with Eq. (2).

PBIAS

 n  obs  Q isim )  100    (Q i i 1    n   ( Q iobs )    i 1

(2)

The coefficient of determination R2 value is an indicator of the strength of the linear relationship between the observed and simulated values. It ranges from 0.0 to 1.0, with higher values indicating better agreement. The R2 is calculated with Eq. (3).

R2 

 n sim sim obs obs    ( Q i  Q mean )( Q i  Q mean   i 1  n

 (Q i 1

sim i

Q

sim mean

)

 (Q i 1

obs i

Q

obs mean

(3) )

3.4 Catchment Management Intervention Scenarios Agricultural conservation practices, often called best management practices or BMPs, are widely used as effective measures for preventing or minimizing pollution from nonpoint sources within agricultural watersheds. SWAT already has an established method for modeling several agricultural practices including changes in fertilizer and pesticide application, tillage Table 1

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operations, crop rotation, dams, wetlands and ponds. The model also has the capacity to represent many other commonly used practices in agricultural fields through alteration of its input parameters [49]. Ten important agricultural conservation practices were selected for representation with the SWAT 2005 model and a number of previous modeling studies have used SWAT to evaluate conservation practices around the globe [50]. However, selection of BMPs and their parameter values are site specific and should reflect the study area reality [21]. For this study, we selected BMPs based on the previous traditional soil and water conservation practices on Ethiopian highlands. Currently, some of these practices are largely under implementation through community based participatory watershed development of Ref. [45], Ethiopia. The baseline values for the input parameters could be selected by: (1) a model calibration procedure; or (2) a “suggested” value obtained from the literature, previous studies in the study area, or prior experience of the analyst [50]. For this study, the baseline values which will represent the basin existing condition (Scenario 0) for the input parameters have been selected based on the suggested value obtained from the literature. For Scenarios 1 and Scenario 2, the BMPs were represented in SWAT model by modifying the SWAT parameters to reflect the effect the practice has on the processes simulated within SWAT [49]. The scenarios simulated and representation of BMPs in the SWAT are depicted in Table 1.

Scenario description and SWAT parameters used to represent BMPs.

Scenarios

Description of BMP

Scenario 0 Scenario 1

Baseline Filter strip

Parameter name

Input file

FILTERW SLSUB

0 0-10% 10-20% 20-260%

SWAT parameter used PRE BMP/Calibration value

Post-BMP/Modified value

0 1m 30 m 17.5 m* 30 m 11 m* BSN Scenario 2 Stone/soil bund 30 m 10min*** CN2 ** ** USLE_P 1.0 0.5 Scenario 3 Reforestation **** **** *The average values taken from Community Based Participatory Watershed Development Guideline; **The calibration value for discharge is maintained; min***minimum value of SLSUBBSN in SWAT model; ****assigned by SWAT model.

Evaluating the Effectiveness of Best Management Practices in Gilgel Gibe Basin Watershed—Ethiopia

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In Scenario 1, filter strips were placed on all CRDY (dry land, cropland and pasture), all soil types and slope classes. The effect of filter strip is to reduce sediment, dissolved contaminants and sediment adsorbed organics in runoff [51]. Appropriate model parameter for representation of the effect of filter strips is FILTERW (width of filter strip). The filter width value, FILTERW, of 1 m was assigned to simulate the impact of filter strips on sediment trapping. The FILTERW value was assigned based on local research experiences in the Ethiopian highlands [52, 53]. In Scenario 2, stone/soil bunds were placed on all CRDY (dry land cropland and pasture), all soil types and slope classes. This practice has a function to reduce overland flow, sheet erosion and reduce slope length [49]. This BMP was selected as it was the most widely and most intensively used soil conservation practice in the area [54]. Appropriate parameters for representing the effect of stone bunds are the CN (curve number), average slope length (SLSUBBSN) and the USLE_P support practice factor (USLE_P). The SWAT assigned value of the USLE_P value of 1.0 is used prior to the application of BMPs. The modified value/Post-BMP value for USLE_P of 0.5 was assigned based on Ref. [52] being the P factor recommended for all types of bunds in Ethiopia. The average slope length (SLSUBBSN) for slopes 0-10% and 10%-20% is taken from the community

based

participatory

watershed

development guideline which is currently under implementation in Ethiopian highlands. The minimum acceptable SLSUBBSN by SWAT is model 10 m and this value is assigned for slopes greater than 20%. In Scenario 3, we simulated the impact of reforestation on sheet erosion. The reforestation has a function to reduce over land flow and rainfall erosivity. The reforestation effect was simulated by introducing land use change. Thus we replaced 1.0% of the area occupied by CRDY (dry land cropland and pasture) in to evergreen forest.

4. Results and Discussion 4.1 Model Calibration and Validation The most sensitive parameters for flow predictions were CN2 (curve number), ALPHA_BF (baseflow alpha factor), GW_DELAY (groundwater delay time), GW_REVAP (ground water “re-vap” co-efficient), REVAPMN (threshold water depth in the shallow aquifer for “revap”), ESCO (soil evaporation compensation factor), SOL_AWC (available water capacity) and CANMX (maximum canopy storage). Table 2 shows the most sensitive parameters and fitted values. These flow parameters were adjusted within the given limits to initiate auto calibration. As measured data is not available on sediment yield, only the modeled data has been used to identify the impact of adjusting a parameter value on some measure of simulated sediment output. Accordingly, most sensitive parameters ranked 1 to 3 were USLE_P (USLE support practice factor), USLE_C (USLE land cover factor), and Ch_K2, respectively. The parameters Ch-Cov (channel cover factor), Ch-erod (channel erodibility factor), exponent of re-entrainment parameter for channel sediment routing (spexp) and linear re-entrainment parameter for channel sediment routing (spcon) were equally important with rank 8. The SWAT flow predictions were calibrated against daily and monthly average flows with a warm up period of three years from 1983 to 1992 and validated from 1993 to 2002 at Asendabo gauging station, as shown in Figs. 2 and 3. The simulated daily flow matched the observed values for calibration period with NSE, PBIAS and R2 equal to 0.684, -13.9% and 0.726, respectively. For the validation period, and the observed daily flows showed acceptable agreement as indicated by NSE, PBIAS and R2 values equal to 0.640, -5.2% and 0.662, respectively. The simulated monthly average flow values also matched the observed values for calibration period with NSE and R2 values equal to 0.54 and 0.886,

Evaluating the Effectiveness of Best Management Practices in Gilgel Gibe Basin Watershedâ&#x20AC;&#x201D;Ethiopia

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Daily discharge calibration at Asendabo gauging station Discharge(m3/s)

300 250 200 150 100

observed

simulated 1983/001 1983/081 1983/161 1983/241 1983/321 1984/036 1984/116 1984/196 1984/276 1984/356 1985/070 1985/150 1985/230 1985/310 1986/025 1986/105 1986/185 1986/265 1986/345 1987/060 1987/140 1987/220 1987/300 1988/015 1988/095 1988/175 1988/255 1988/335 1989/049 1989/129 1989/209 1989/289 1990/004 1990/084 1990/164 1990/244 1990/324 1991/039 1991/119 1991/199 1991/279 1991/359 1992/074 1992/154 1992/234 1992/314

Year/day

(a)

400 350 300 250 200 150 100 50 0

observed simulated

1993/001 1993/081 1993/161 1993/241 1993/321 1994/036 1994/116 1994/196 1994/276 1994/356 1995/071 1995/151 1995/231 1995/311 1996/026 1996/106 1996/186 1996/266 1996/346 1997/060 1997/140 1997/220 1997/300 1998/015 1998/095 1998/175 1998/255 1998/335 1999/050 1999/130 1999/210 1999/290 2000/005 2000/085 2000/165 2000/245 2000/325

Discharge(m3/s)

Daily discharge validation at Asendabo gauging station

Fig. 2

Year/day (b) Observed and simulated daily hydrographs at Asendabo Station: (a) calibration; (b) validation.

respectively. The calibration parameters were checked for the validation period and found to be 0.629 and 0.696 for NSE and R2, respectively. The model simulated well the discharge on the rising limb of the hydrograph. While, the falling limb of the hydrograph indicated that the simulated discharge is slightly greater than the observed discharge data for the whole calibration and validation period, and the crest segment of the hydrograph show the simulated peak discharge to be slightly less than the observed peak discharge. Generally, as it was shown by model performance evaluation criteria, the SWAT model performed well in simulating stream flow hydrograph for this study. Besides, the performance of SWAT model, Ndomba and Griensven [55] indicated that the SWAT model can satisfactorily estimate sediment yield for even poorly

gauged catchments of East African countries. 4.2 Scenario Analysis The assessment of the spatial variability of soil erosion is useful for catchment management planning [12]. The soil erosion prone areas in the Gilgel Gibe-1 basin are shown in Fig. 4 The SWAT model simulation shows erosion extent varies from negligible erosion to 39 t/ha. Based on the classification of erosion rates in the Ethiopian highlands [56] the erosion level which are classified as high and very high in sub-basin 1, 3, 5 and 8 of Gilgel Gibe-1 basin corresponds to moderate erosion level (20-70 t/ha/yr). The erosion level in the sub basin 1, 3, 5, and 8 is in the range of 20 t/ha to the maximum value of 39 t/ha. The erosion level which are indicated as medium in sub-basins-2, 38 and 46 are relative to

Evaluating the Effectiveness of Best Management Practices in Gilgel Gibe Basin Watershedâ&#x20AC;&#x201D;Ethiopia

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Discharge(m3/s)

Monthly discharge calibration at Asendabo Gauging station

200 150 100

observed

simulated

0 Year/Month

(a)

observed

Simulated

1993\1 1993\3 1993\5 1993\7 1993\9 1993\11 1994\1 1994\3 1994\5 1994\7 1994\9 1994\11 1995\1 1995\3 1995\5 1995\7 1995\9 1995\11 1996\1 1996\3 1996\5 1996\7 1996\9 1996\11 1997\1 1997\3 1997\5 1997\7 1997\9 1997\11 1998\1 1998\3 1998\5 1998\7 1998\9 1998\11 1999\1 1999\3 1999\5 1999\7 1999\9 1999\11 2000\1 2000\3 2000\5 2000\7 2000\9 2000\11

Discharge(m3/s)

Monthly discharge Validation at Asendabo gauging station 200 180 160 140 120 100 80 60 40 20 0

Year/month

Fig. 3 Table 2

(b) Observed and simulated monthly hydrographs at Asendabo Station: (a) calibration; (b) validation. SWAT sensitive parameters and fitted values.

Parameter name m-CN2.mgt* a-ALPHA_BF.gw** r-GW_DELAY.gw r-GW_REVAP.gw r-REVAPMN.gw r-ESCO.hru m-SOL_AWC.sol a-CANMX.hru

Description Curve number Base flow alpha factor Groundwater delay time Groundwater revap co-efficient Threshold water depth in the shallow aquifer for revap Soil evaporation compensation factor Available water capacity Maximum canopy storage

Parameter value 0.8 0.302 45 0.20 0.15 0.25 1.67 4

*The extension (e.g., .mgt) refers to the SWAT input file where the parameter occurs; **The qualifier (a-) refers to the substitution of a parameter by adding the parameter values indicated in Table 2 and (m-) refers to the relative change in the parameter where the value from the SWAT database is multiplied by the values in the table. And (r-) refers to replacement in the parameter from the SWAT database by the values indicated in the table.

remaining sub-basins and their erosion level is in the range of 10 t/ha to 20 t/ha. Generally, the SWAT simulation results for Gilgel Gibe-1 basin indicate that the sub-basins 1, 2, 3, 5, 8, 38 and 46 have the high rate of erosion relative to the remaining sub-basins.

The sub-basins with high rate of erosion have a maximum percentage of nearly 60% land-use of CRDY (dry land cropland and pasture) while the sub-basins with very low soil erosion rate have got 0-9% dry land, cropland and pasture as their landuse.

Evaluating the Effectiveness of Best Management Practices in Gilgel Gibe Basin Watershed—Ethiopia

These simulation results show the relative variations of soil erosion level within a sub-basin. These results are helpful to prioritize BMPs implementation area. Moreover, these results showed that the sediment yield to Gilgel Gibe-1 reservoir is mainly from sub-basins of the tributaries of Nedhi, and Bulbul which are to the left side of Gilgel Gibe River and at a close proximity to the reservoir. The SWAT model simulation for the existing condition predicted the sediment yield at the outlet of Gilgel Gibe-1 basin, which is an inlet to Gilgel Gibe dam reservoir to be 122.73 × 103 t/yr. However, running the model with different catchment management scenarios provided interesting results. The simulation of filter strips scenario reduced the total sediment yield to 79.82 × 103 t/yr from current condition at the same outlet location, which is equivalent to 35% reduction. The simulation of stone/soil bunds reduced the sediment yield to 23.26 × 103 t/yr from the current conditions, which is equivalent to 81% reduction. This result is comparable to the results reported in the literature. Herweg and Luid [53] reported 72%-100% sediment yield reductions by stone bunds at plot scale in Ethiopian

SYLDsc0 <all other values>

Erosion High Low Medium V.High

Fig. 4

9,500

19,000

Erosion prone areas in Gilgel Gibe basin.

and the Eritrean highlands. The simulation of reforestation scenario (Scenario 3) showed the average reduction of sediment yield by 9.1% for sub-basins 1, 3, 5, 8, 2, 38 and 46 from the current condition. This less sediment reduction under Scenario 3 as compared to Scenario 1 and 2 could be attributed to smaller implementation area. The average sediment reduction at sub-basin level where the sub-basin has got dry land CRDY greater than 10% of its total area under filter strip scenario was 35%. This is comparable with results reported by Betrie et al. [21]. They reported the sediment reductions under filter strip scenario ranged from 29% to 68%. In this study, the percentage sediment yield reduction per ha at sub-basin level increased with an increase in the percentage area of CRDY which was provided with filter strip width of 1 m. The sub-basins such as sub-basins 15, 16, 23, 48 and 50 with percentage area of dry land, CRDY (cropland and pasture) less than 10% showed the sediment yield reduction efficiency of 0% under filter strip scenario. The effectiveness of BMPs per hectare for the sub-basins with different percentage of dry land, CRDY (cropland and pasture) is shown in Fig. 5.

Legend

38,000 Meters

1249

Evaluating the Effectiveness of Best Management Practices in Gilgel Gibe Basin Watershedâ&#x20AC;&#x201D;Ethiopia

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Percentage reduction

Percentage sediment yield reduction of bund

filter strip and stone

90 80 70

AREA(%)

60 50

FILTER(%)

STONE BUND(%)

30 20 10 0

Fig. 5 Percentage of CRDY in the subbasin and sediment reduction efficiency of Scenarios 1 and 2.

5. Conclusions The SWAT model was applied to assess the impact of the three BMPs (best management practices) scenarios on sediment reduction in the Gilgel Gibe river basin. The impact of further subdivision of the sub-basins in to more number of HRUs on the effectiveness of BMPs on sediment reduction was also checked. The model showed that the erosion prone areas at sub-basin level, which is useful information for catchment management planning and for the implementation of the watershed development program. The watershed development program through community based participatory approach under implementation throughout the country. This study result showed that the implementation of the three BMPs could reduce the soil erosion and sediment yield at the sub-basin and basin level. One of the three BMPs, namely soil/stone bunds has been practiced and implemented in some of the districts in the study watershed. The same practice is widely under implementation in Gilgel Gibe basin as per the decision made by the Ethiopian Government to promote and expand community watershed development in the country. However, the cost of implementing the BMPs should be evaluated. Additional BMPs should also be investigated and the best ones combined to form other scenarios which reduce soil erosion and sedimentation. This study

shows as the modeling approach could be helpful for decision makers to prioritize the areas of intervention. In order to obtain a better estimate of the effectiveness of the filter strips, further investigation should be undertaken by using the improved VFS (vegetative filter strip) sub-model of SWAT 2009 version. Furthermore, SWAT 2009_LUC, a tool to activate the land use change module in SWAT 2009 should be applied for further investigations.

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Strategies for reducing soil degradation through modeling in a GIS environment in northern Ethiopia catchment, Nutrient Cycling in Agroecosystems 92 (2012) 255-272. M.T. Asres, S.B. Awulachew, SWAT based runoff and sediment yield modeling, a case study of the Gumera watershed in the Blue Nile Basin, Ecohydrology and Hydrobiology 10 (2010) 191-200. G.D. Betrie, Y.A. Mohamed, A. van Griensven, R. Srinivasan, Sediment management modeling in the Blue Nile Basin using SWAT model, Hydrol. Earth Syst. Sci. 15 (2011) 807-818. Community Based Participatory Watershed Development, Part 1: A Guideline, MOARD (Ministry of Agriculture and Rural Development), Addis Ababa, Ethiopia, 2005. S.L. Neitsch, J.G. Arnold, J. Kiniry, J.R. Williams, Soil and Water Assessment Tool Theoretical Documentation (Version 2005), USDA Agricultural Research Services and Texas A & M Blackland Research Center, Temple, Texas, 2005. National Engineering Handbook, Section IV, Hydrology, USDA-SCS (US Department of Agriculture-Soil Conservation Service, 1972. W.H. Green, C.A. Ampt, Studies on soil physics: I. Flow of air and water through soils, J. Agr. Sci. 4 (1911) 1-24. J.R. Williams, Flood routing with variable travel time or variable storage coefficients, T. ASAE 12 (1969) 100-103. V.T. Chow, Open Channel Hydraulics, McGraw-Hill Book Company, New York, 1959. C. Priestley, R. Taylor, On the assessment of surface heat flux and evaporation using large-scale parameters, Mon. Weather Rev. 100 (1972) 81-92. J.L. Monteith, Evaporation and environment, Symp. Soc. Exp. Biol. 19 (1965) 205-234. G. Hargreaves, G. Hargreaves, J. Riley, Agricultural benefits for Senegal river basin, J. Irrig. Drain. E-ASCE 111 (1985) 113-124. J. Williams, H. Berndt, Sediment yield prediction based on watershed hydrology, T. ASAE 20 (1977) 1100-1104. J.G. Arnold, J.R. Williams, D.R. Maidment, Continuous time water and sediment-routing model for large basins, J. Hydraul. Eng-ASCE 121 (1995) 171-183. J. Williams, SPNM: A model for predicting sediment, Phosphorus, and nitrogen yields from agricultural basins, J. Am. Water. Resour. As. 16 (1980) 843-848. C. George, L.F. Leon, Water base: SWAT in an open source GIS, The Open Hydrology Journal 2 (2008) 1-6. A. Jarvis, H.I. Reuter, A. Nelson, E. Guevara, Hole-filled Seamless SRTM Data Version 4, International Centre for Tropical Agriculuture (CIAT), 2008, http://srtm.csi.cgiar.org (accessed Mar. 25, 2012). M. Hansen, R. DeFries, J. Townshend, R. Sohlberg, 1 km

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Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1253-1259 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

DAVID

PUBLISHING

Performance of a Nonwoven Geotextile Reinforced Wall with Unsaturated Fine Backfill Soil Fernando Henrique Martins Portelinha1, Benedito de Souza Bueno2 and Jorge Gabriel Zornberg3 1. Department of Civil Engineering, Federal University of Sao Carlos, Sao Carlos/SP 13564-350, Brazil 2. Sao Carlos Engineering School, University of Sao Paulo, Sao Carlos/SP 13566-536, Brazil 3. Civil Engineering Department, University of Texas at Austin, Austin/TX 78712-0280, USA Abstract: The use of marginal backfills in GSE (geosynthetic stabilized earth) walls has not been recommended by different standards specifications. Restrictions are motivated by the poor hydraulic conductivity of fine soils that are capable of developing of water pressures. However, the use of granular materials can expend the cost of the construction. As a result, local soils, granular or not, have been increasingly used. Unsaturated conditions of fine soils may result in convenient performance even using extensible reinforcements. This paper evaluates the performance of a full scale model of a nonwoven geotextile reinforced wall constructed with fine grained soil backfill. The unsaturated condition was maintained and matric suctions, displacements and reinforcement strains were monitored during the test. Results have shown that the unsaturated condition of the backfill allowed maximum reinforcement peak strain of 0.4 %. For the case of a wrap faced wall on a firm foundation the performance and good agreement between measured strains and factors of safety from limit equilibrium analyses have shown the maintenance of unsaturated conditions as an economical alternative to the use of high quality fill. Key words: Reinforced soil wall, nonwoven geotextile, fine soil, unsaturated soil.

1. Introductionď&#x20AC; Since the reinforced soil technique began to be used in retaining walls, embankments and slopes, standard organizations have been concerned about the hydraulic behavior of poorly draining backfill soils [1, 2]. The major problems are the development of positive water pressures inside the reinforced zone and reinforcement interaction in the presence of water. In fact, the low draining capacity of fine soils can affect the reinforced soil walls performance under rainfall infiltration as reported by Yoo and Jung [3] and Fowze et al. [4]. On the other hand, an excellent performance can be expected from these structures under unsaturated conditions due to the positive effect of matric suction on soil and interface behavior. Khoury et al. [5] report that pullout strength of Corresponding author: Fernando Henrique Martins Portelinha, Ph.D., research fields: development of concepts, methodologies and tools focused at the geosynthetic technologies applied to geotechnical engineering. E-mail: fportelinha@gmail.com.

geotextiles embedded in unsaturated soils are so influenced by matric suction as shear strength of soils. Additionally, some real cases reported in the literature could confirm the strong influence of unsaturated conditions of backfill on the performance of geosynthetic reinforced soil walls [6, 7]. The maintenance of unsaturated conditions of backfill soils is a difficult task regarding field conditions. Koerner and Soong [8] recommend avoiding any possible water in the front, behind and beneath the reinforced zone collecting, transmitting and discharging the water. Furthermore, the top of the zone should be waterproofed, e.g., by a geomembrane or a geosynthetic clay liner, to prevent water from entering the backfill zone from the surface. However, Wayne and Wilcosky [9] reported that use of nonwoven geotextiles assisted in maintaining fine grained soils in an unsaturated condition in the reconstruction of failed slope, since the hydraulic properties of nonwoven geotextile reinforcements can be useful to

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Performance of a Nonwoven Geotextile Reinforced Wall with Unsaturated Fine Backfill Soil

dissipate pore water pressures and, consequently, enhance the internal stability of the structure [10, 11]. Matric suction can improve the walls performance in two aspects: increasing the soil stiffness and improving the interface shear strength behavior. Therefore, two design implications can be drawn from these aspects: a stiffer soil favors the selection of lower stiffness reinforcements, resulting in reductions of costs; and, convenient interface behavior provides a good transmission and mobilization of forces by the reinforcement. This paper describes the performance of an instrumented full scale model of a nonwoven geotextile reinforced soil wall under unsaturated backfill conditions.

2. Experimental Program 2.1 Materials Full scale models were constructed using clayey sand with a hydraulic conductivity of 5 Ă&#x2014; 10-6 cm/s, with 40% passing the No. 200 sieve, and low plasticity (PI = 18%). Compaction parameters from standard Proctor tests are maximum dry unit weight of 17.8 kN/m3 and optimum water content of 14.6%. With the relative low hydraulic conductivity and significant percentages of fine particles, this material would be restricted from use by AASHTO [2] and FHWA [1], being classified as a poorly draining soil. Triaxial tests in unsaturated soil samples indicated cohesion of 0 kPa and friction angle of 38o for CD (consolidated drained) tests and, cohesion of 60 kPa and friction angle of 25o for CU (consolidated undrained) tests, in terms of total stresses. The reinforcement consisted of a polyester needle-punched nonwoven geotextile made of polyester with a mass per unit area of 293 g/m2, thickness of 2.69 mm, tensile strength of 10 kN/m and strain at failure of 83% (testing was performed in accordance with ASTM D4595). A relatively weak and extensible geotextile was specifically selected to

generate detectable strain levels. 2.2 Full Scale Model Construction Full scale walls have been constructed in the Laboratory of Geosynthetics located within the Sao Carlos School of Engineering at the University of Sao Paulo. A metallic box allows reinforced soil wall structures to be constructed with 1.8 m height by 1.55 m width, with backfill soil extending to a distance of 1.8 m from the front edge of the metallic box. The soil was compacted at 98% of relative density and the maximum dry unit weight and optimum water content from standard Proctor tests. In order to assure the required relative density, compaction was performed manually in layers of 5 cm height. Compaction control was assured by the drive-cylinder method (ASTM D2937), spiked every compacted layer reaching 30 cm height. The backfill soil was seated on a rigid concrete foundation. Geotextile reinforcements were placed at 30 cm vertical spacing with declivity of 1% to the face. Each layer of reinforcement had a total length of 1.80 m measured from the face. The wall was constructed with no facing batter and using the wrapped-around technique. Protective shotcrete coating varying from 5 cm to 8 cm was used. Drainage geocomposites were used as face drainage elements into the second and forth reinforced layers located at 30 cm from the face forward into the wall. Fig. 1 presents the cross section view of the model. 2.3 Instrumentation Instrumentation was deployed to record pore water pressures including negatives values (soil suction), internal horizontal displacements, reinforcement strains and horizontal face displacements. Instruments locations are presented in Fig. 2. Matric suction was monitored by tensiometers (range of -100 kPa to 100 kPa) located in the middle of each reinforced layer at 5 cm above the reinforcements at a distance of 80 cm and 140 cm from the face.

Performance of a Nonwoven Geotextile Reinforced Wall with Unsaturated Fine Backfill Soil

Airbag

Acquisition system

Facing drains

Shotcrete facing

i=1%

Drainage geocomposites

4 Reinforcement layers 3

165

Reaction lid

1255

2 1

Shotcrete facing

Steel beam

(cm) Fig. 1

(a) Frontal photograph Geotextile reinforced soil wall model. Tensiometer INSTRUMENTS Water content sensor Tensiometers Earth pressure cells Tell tails Dial indicators

Base layer

180 160

Soil

Concrete

(b) Cross section

model under a uniform loading of 100 kPa. Instrumentation records were maintained from the beginning of construction and throughout the initial 90 days of loading.

3. Results Reinforcement layers Base layer

Soil Concrete

Fig. 2

Instruments location.

Internal displacements were measured by tell-tales. These devices consisted of stainless steel inextensible wires, which run inside of plastic tubes used to reduce friction and to protect the wires. One end of the tell-tales is fixed to the geotextile and the opposite is connected to a small weight that is used to tension the wires and to obtain measures. Relative displacements between the weight and a reference located in a shaft behind the wall were measured during the test. Tell-tales were fixed at five points along reinforcements at 30 cm of horizontal spacing. Other displacement instruments were used in this research but they will not be assessed in this paper. 2.4 Test Procedure The test procedure involved recording of instrumentation incorporated within the full scale

3.1 Instrumentation Results Fig. 3 presents results from tensiometers installed at 80 cm and 140 cm from the face in each instrumented layer of the model. In general, the initial matric suctions of soil were similar for all reinforced layers and increases of matric suction were observed with time. Higher rates of matric suction increasing occurred in the lower layers, with values varying from 20 kPa to 80 kPa. In higher layers, matric suction values ranged from 20 kPa to 30 kPa. Internal displacements measured by tell-tales with time are shown in Fig. 4. This figure presents readings in points located at 0 cm, 30 cm, 60 cm, 90 cm, 120 cm and 150 cm from the wall face. Clearly, higher rates of displacement increases occurred as soon as the loading of 100 kPa was applied to the top of the wall. Thereafter, small increases could be evidenced with time. In the reinforced layer 2, displacements were practically constants throughout loading. Possibly, high values of matric suction of soil during the wall life avoided reinforcement creep strains,

Performance of a Nonwoven Geotextile Reinforced Wall with Unsaturated Fine Backfill Soil

1256 100

Reinforced layer 5

2.0

80 cm from the face

140 cm from the face

30 cm from the face

face

Loading of 100 kPa

1.0

60 cm 90 cm 120 cm

0.5

20 0 100

Reinforced layer 4

150 cm

0.0 1.0

80 cm from the face

Reinforced layer 4

140 cm from the face

Internal displacement (mm)

60 Matric Suction, ua-uw(kPa)

Reinforced layer 5

1.5

40 20 0 100

Reinforced layer 3

80 60 40

face 30 cm from theface

Loading of 100 kPa

0.5 60 cm 90 cm 120 cm

0.0 1.5

Reinforced layer 3

30 cm from the face

face

Loading of 100 kPa

1.0

120 cm

0.5

60 cm

80 cm from the face

90 cm

140 cm from the face

0 100

0.0 1.5

Reinforced layer 2

face

1.0

60 40

30 cm from the face

0.5 80 cm from the face

140 cm from the face

0 0

10 10

20 20

30 30

40 40

50 50

60 60

70 70

80 80

90 100 100 90

Time (days)

Fig. 3 Matric suction measured by tensiometers with time at 80 cm and 140 cm from the wall face.

150 cm

120 cm

0.0

100

90 cm

60 cm

Fig. 4

Internal displacements versus time.

3.2 Strains in the Geotextiles Reinforcement strains were obtained from the relative horizontal displacements between facing and tell-tales attached along the reinforcement length at different distances. The distribution of relative displacement along the reinforcement between points of measurements and wall facing in the reinforced layer 2 is presented in Fig. 5. In this figure, sigmoidal curves fitting the raw data are drawn in order to have a smooth representation of the distribution of displacements along the reinforcement length. The sigmoidal fitting shown in Fig. 5 was also used to evaluate the distribution of strains along the reinforcement as presented by Zornberg and Arriaga

Relative displacement (mm)

1.2

resulting in a relatively rigid structure. This was substantiated due to the presence of the concrete foundation which limits deformation to the reinforced zone of the structure.

1 0.8

0 days 6 days 8 days 14 days 31 days 35 days 41 days 47 days 59 days 68 days 90 days

0.6 0.4 0.2 0 00

300 300

600 900 1200 600 900 1,200 Distance from the face (mm)

1500 1,500

Fig. 5 Distribution of relative displacements between tell tales and wall face along the geotextile length.

[12]. Geotextile strains values can be obtained by calculating relative movements between points of tell tales at different distance from the reference and dividing them by the initial distance between rods. However, the use of this technique may not be efficient in this case, since the distance between measured points may not be small enough to get a real

Performance of a Nonwoven Geotextile Reinforced Wall with Unsaturated Fine Backfill Soil

  1  / dx   cx   a  be 

  d 

(1)

where, d is the tell-tale displacement, x is the distance from the wall face to the measured point, and a, b and c are parameters defined by the fitting of sigmoidal curves to the raw data using the minimum squares technique. This technique was used in a GSE field case by Zornberg et al. [13]. The distribution of strains in each instrumented layer is shown in Fig. 6. The strain levels were very small with a maximum value of 0.43% in the reinforced layer 2 and minimum value of 0.15% in the reinforced layer 4. Additionally, no relaxation or

[15]. This software allows for analysis of slopes and walls considering the reinforcement contribution and interpolating negative pore water pressures (matric suction) in the soil. The effect of matric suction on the factor of safety and reinforcement peak strains can be better understood through examination of Fig. 7, where the factor of safety and reinforcement peak strains are plotted as function of the average of matric suction measured by all the tensiometers installed in the model. From this plot, the factors of safety increased linearly with matric suction and a better stability could be noted with the time. No significant changes in measured values of peak strains with matric suction could be evidenced, and significantly small levels of strains were noticed. Therefore, small forces were mobilized by reinforcement, and, possibly, this structure would be

retraction of reinforcements could be observed. the derivation of a sigmoidal fitting curve and a Rankine failure surface seems to properly fit it, assuming a friction angle from C-U triaxial tests on unsaturated samples. The effect of matric suction on the stiffness of soil can be a good explanation for very small strains and

Geotextile strains (%)

A consistent distribution of strains was obtained by

displacements even using extensible reinforcements as

0,2 0.2 0.1 0,1 00 0,2 0.2 0,1 0.1 00 0,2 0.2 0.1 0,1 00 0,4 0.4 0.2 0,2 00

Days after construction: 0 days 6 days 8 days 14 days 31 days 35 days 41 days 47 days 59 days

300 300

600 600 Rankine failure surface

nonwoven geotextiles. Additionally, interface shear behavior is absolutely improved under unsaturated Fig. 6

consideration is the tensile and creep behavior of

Distribution of strains. 1 Factor of safety x Average of matric suction

nonwoven geotextiles under confined conditions [14].

Peak strains x Average of matric suction

These influences are not discussed as part of this

Factors of safety were calculated by limit equilibrium analyses in order to compare design parameters and measured values. Limit equilibrium analyses were conducted using the technical software UTEXAS3 from the University of Texas, by Wright

0.8

2.5

Factor of safety

3.3 Limit Equilibrium Analysis

1,200 1200 1,500 1500

Distance from the face (mm)

conditions [5]. Other aspects requiring further

paper as they are covered in detail elsewhere [1].

900 900

0.6

2 0.4

1.5

Saturated condition (suction zero)

Peak strains (%)

strain between points. For this reason, the raw data from tell tales was initially smoothed by fitting the data to a sigmoidal curve. Thus, the distribution of strains along the geotextile length could be obtained by deriving the displacement function as:

1257

0.2

-10

Average of matric suction (kPa)

Fig. 7 Limit equilibrium analyses: effect of matric suction on factors of safety and reinforcement peak strains.

Performance of a Nonwoven Geotextile Reinforced Wall with Unsaturated Fine Backfill Soil

1258 150

120

H (cm)

Days after construction: 14 dias 14 days 41 dias 41 days

Predicted

68 dias 68 days 90 days 90 dias 14 dias 14 days

41 dias 41 days

Measured

68 dias 68 days 90 dias 90 days

300 300

600 600

900 900

1200 1,500 1500 1,200

Distance from the face (mm)

Fig 8 Slip surfaces from equilibrium limit analyses in different times.

stable even without reinforcements. In this case, reinforcements perform purely the constructability function. Fig. 8 summarizes the slip surfaces obtained from limit equilibrium analyses inputting matric suction values. This analysis was conducted in order to compare failure surface location from measured peak strains and predicted slip surface. Rankine failure surface (Fig. 6) showed better agreement than a circular slip surface from limit equilibrium analyses, even though factors of safety using Rankine stress state are much more conservative. Additionally, no influence of matric suction was observed on potential slip surface shapes, nor failure surfaces from measured strains.

changes on peak strains with time were noted in this study. Thus, creep strains potentials seem to be minimized by the soil matric suction, even though creep occurs over a significantly longer period than that exploited in this study; (3) Limit equilibrium analyses have shown the increase of factor of safety with matric suction. The relationship between reinforcement peak strains with increasing factor of safety was horizontally linear, which means no changes of strains with matric suction; (4) Small forces were mobilized by reinforcement, and, possibly, this structure would be stable even without reinforcements. In this case, reinforcements served the function of “internal drainage” which supports the work by Wayne and Wilcosky [9]. Therefore, the structure have proved to work significantly well under unsaturated condition due to the increase of soil stiffness. As a result, small forces are transmitted to the reinforcements and low strength material can be adopted. Restriction of wetting front by means of an internal drainage system and/or water barriers, and the use of unsaturated poorly draining soils, can be an economical alternative for retaining walls or reinforced slopes.

References [1]

[2]

4. Conclusions The following conclusions can be drawn from the analysis of the data collected as part of this investigation: (1) Significantly small internal displacements and reinforcement strains illustrated the positive effect of matric suction on the wall’s performance; (2) Although the matric suction increased with time, no reinforcement retraction was observed. Still, no

[3]

[4]

[5]

V. Elias, B.R. Christopher, Mechanically Stabilized Earth Walls and Reinforced Soil Slopes Design and Construction Guidelines, FHWA (Federal Highway Administration), FHWA-SA-96-071, Washington, DC, 2010, p. 371. Standard Specifications for Highway Bridges, 17th ed., AASHTO (American Association of State Highway and Transportation Officials), 2002. C. Yoo, H.Y. Jung. Case history of geosynthetic reinforced segmental retaining wall failure, Journal of Geotechnical and Geoenvironmental Engineering 132 (12) (2006) 1538-1548. J.S. Fowze, D.T. Bergado, S. Soralump, M. Voottipreux, Rain-triggered landslides hazards and mitigation measures in Thailand: From research to practice, Geotextile and Geomembranes 30 (1) (2012) 50-64. C.N. Khoury, G.A. Miller, K. Hatami, Unsaturated soil-geotextile interface behavior, Geotextile and

Performance of a Nonwoven Geotextile Reinforced Wall with Unsaturated Fine Backfill Soil Geomembranes 29 (2010) 17-28. M. Ehrlich, D. Vidal., P.A. Carvalho, Performance of two geotextile reinforced soil slopes, in: Proceedings of International Symposium on Recent Developments in Soil and Pavement Mechanics, 1997, pp. 415-420. [7] F.H.M. Portelinha, B.S. Bueno, J.G. Zornberg, Performance of nonwoven geotextiles reinforced soil walls under wetting conditions: Laboratory and field investigation, Geosynthetics International 20 (2) 90-104. [8] R.M. Koerner, T.Y. Soong, Geosynthetic reinforced segmental retaining walls, Geotextiles and Geomembranes 19 (6) (2001) 359-386. [9] M.H. Wayne, E. Wilcosky, An innovative use of a nonwoven geotextile in the repair of Pennsylvania State Route 54, Geotechnical Fabrics Report 14 (7) (1996) 26-29. [10] D.V. Raisinghani, B.V.S. Viswanadham, Evaluation of permeability characteristics of a geosynthetic-reinforced soil through laboratory tests, Geotextile and Geomembranes 28 (6) (2010) 579-588.

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[11] D.V. Raisinghani, B.V.S. Viswanadham, Centrifuge model study on low permeable slope reinforced by hybrid geosynthetics, Geotextile and Geomembranes 28 (6) (2011) 579-588. [12] J.G. Zornberg, F. Arriaga, Strain distribution within geosynthetic-reinforced slopes, Journal of Geotechnical and Geoenvironmental Engineering 129 (1) (2003) 32-34. [13] J.G. Zornberg, B.R. Christopher, J.K. Mitchell, Performance of a geotextile reinforced slope using decomposed granite as backfill material, in: Proceedings of Second Brazilan Simposium on Geosynthetics Applications, S達o Paulo, 1995, pp. 19-29. [14] A. McGown., K.Z. Andrawes, M.H. Kabir, Load-extension testing of geotextiles confined in-soil, in: Proceedings of International Conference on Geotextiles, USA, 1982, pp. 793-798. [15] S.G. Wright, UTEXAS3: A Computer Program for Slope Stability Analyses Calculation, Shinoak Software, Austin, Texas, 1990.

Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1260-1266 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

DAVID

PUBLISHING

Models and Optimization of Rice Husk Ash-Clay Soil Stabilization Iloeje Amechi Francis1 and Aniago Venantus2 1. Department of Architecture, Enugu State University of Science and Technology, Enugu 400261, Nigeria 2. Department of Civil Engineering, Enugu State University of Science and Technology, Enugu 400261, Nigeria Abstract: Soil stabilization has been found to be very effective in upgrading the bearing capacity of weak soils for construction purposes. The stabilizing agent, for cost efficiency, ought to provide a cheaper alternative to other possible processes. With the rapid industrialization efforts around the globe, enormous quantities of waste materials are generated and there has not been adequate mechanism for recycling and re-use of such wastes to reduce the consequent environmental problems and hazardous situations created as a result. The objective of the study is to upgrade expansive soils from Eke Obinagu, Ugwuaji in Enugu State and Egbede in Abia State Nigeria, as constructions material using RHA (rice husk ash). Expansive clay soils were mixed with this ash, remolded and tested to examine the effect on the OMC (optimum moisture content) and the CBR (California Bearing Ratio). The characterization of the soils was done in accordance with BS1377 and 1990b, with respect to their engineering properties which include OMC, MDD, Soaked CBR, Liquid Limit, Classification and Sieve Analysis. The rice husk was burnt and prepared in a cylindrical incinerator to form the ash. The results of classification showed A-7-5, A-6, A-2-7 soils for Eke Obinagu, Egbede and Ugwuaji, respectively. The CBR values showed increase from 5% to 29%, 7% to 13% and 5% to 23% for A-7-5, A-6 and A-2-7 respectively at optimal value of 17.5% stabilization. There was also an appreciable increase in the OMC values from 15% to 33%, 14% to 25% and 15% to 31% for A-7-5, A-6 and A-2-7 soils respectively at 17.5% stabilization. Empirical models based on Scheffe’s model were developed with the experimental results and the equations resulting from the second degree polynomials of Scheffe’s models were solved using the least square method. The models developed showed close correlation with the experimental results for the A-7-5 and A-6 soils and will form good guide in pavement and foundation designs in the study areas. Key words: Models, stabilization, CBR, RHA, clay.

1. Introduction Soil as a material is easily the most abundant of all natural resources but yet very scarce when needed as a construction material. In developing countries, demand for this material is on a daily increase. With increase in road and building construction activities in the southeastern Nigeria, high demand has been placed on the soil with the result that those that qualify for use for construction purposes are almost out of stock. This creates an urgent need, in Nigeria as well as other areas round the globe, for increased effort towards improving any available soil, for use, within the locality. In road construction, the Corresponding author: Iloeje Amechi Francis, M.Sc., research field: environmental management/architecture. E-mail: get2frankfast@gmail.com.

underlying principle is to employ high quality sub grade materials to effect a substantial reduction in the thickness of pavement, thereby effectively reducing the overall cost of construction while still maintaining a long life span for the constructed road. In the southeastern Nigeria, quality soils used for sub grade are in very short supply. Others are largely deficient in their engineering properties making them very unfit for use in construction and thus requiring some degree of stabilization to enhance the quality before use. In Enugu and Abia States, the study areas, huge quantities of waste materials are produced and the disposal mechanism does not match the rate of production, thereby creating environmental problems and hazardous situations. Adequate and safe disposal of such materials are very vital and can be addressed

Models and Optimization of Rice Husk Ash-Clay Soil Stabilization

1261

by finding ways to improve and utilize them for other useful purposes. Numerous works have been done on stabilization of soil using waste products and these

et al. [7], used ash from rice mill and lime sludge from paper factory (all waste products), to demonstrate that the PI (plasticity index) value of clay soil decreases

have been able to prove that a substantial percentage of wastes when combined with other materials can produce highly beneficial results. One such material produced in large quantities, in the study areas, without adequate disposal plan, is the RHA (rice husk ash). This material can be harnessed and effectively

from twelve to eight when mixed with 10% ash and 16% lime sludge. Furthermore, with increase in the proportions of these materials, the dry density of the soil decreases whereas the OMC (optimum moisture content) increases. The UCS (unconfined compressive strength) was observed to have optimal value

used in combination with other materials to produce useful results. It has been classified into high carbon char, low carbon ash and carbon free ash [1]. Due to its refractory properties, it is most wanted in steel, ceramic and brick factories [2]. Several researchers carried out experimental studies

corresponding to 10% ash and 16% lime sludge. The soaked CBR value increases with increase in these materials. The optimal values of the proportions of these two materials for maximum UCS and lowest PI were estimated to be about 10% and 16%, respectively. These results showed that these materials are excellent

on the use of this material to upgrade the soil properties. A study on strength characteristics of clay soil stabilized with lime and the ash was conducted by Ref. [3]. The unconfined compressive strength and soaked CBR (California Bearing Ratio) tests for different combinations of the stabilizing agents

additives, in optimal proportions, for the stabilization of clayey soil. The stabilized soils can then be successfully employed for use as sub grade or sub-base for roads or pavement construction. While saving in construction costs, the environment is also rid of enormous deposits of waste.

showed that 4% lime is very close to the optimal value either as sole additive or with any other secondary additive, from the view point of optimum efficacy. Ali and Sreenivasulu [4], also carried out an experimental investigation on the influence of the ash and lime on the Atterbergâ&#x20AC;&#x2122;s limits, strength, compaction, swell and

Soil stabilization generally has been found to be useful in upgrading the bearing capacity of weak soils for building purposes. This has increased the potential benefits of using some waste products, against cement, as stabilizing agents. The major challenge now is to develop mathematical models that will encourage wider and easier application of soil improvement techniques. This study will examine the use of the ash to upgrade an expansive clay soil, for use as a construction material. The percentage of this material that will generate better result in the engineering properties of the soil will also be examined with a view to formulating a model for RHA-Clay soil stabilization.

consolidation properties of bentonite. The results showed that the plasticity properties of bentonite were significantly modified upon their addition. There was also a noticeable influence of these materials on compaction, strength, swell and consolidation properties of bentonite soil particularly at 15% and 8% stabilization, respectively. Another study carried out by Chattopadhyay and Roy [5], explored the possibility of alternative materials like pond ash to be used wholly or partially for the construction of roads as well as manufacture of bricks. Mahmud and Muntohar [6], examined the possibilities of improving residual soil properties with this ash and cement in suitable proportions as stabilizing agents. Chandra

2. Materials and Methods 2.1 Study Areas The soil samples were collected from three different locations of Enugu and Abia states, in the

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Models and Optimization of Rice Husk Ash-Clay Soil Stabilization

southeastern Nigeria. These locations are Borrow Pit sites for most of the road contracting firms in the states and they include: Eke-Obinagu Borrow Pit, Nike, Enugu state; Egbede Borrow Pit, Aba, Abia state and Ugwuaji Borrow Pit, Nkanu, Enugu state. 2.2 Characterization of Clays Clays are rarely formed separately. They are mixed with other materials such as microscopic crystals of carbonates, feldspars, micas and quarts. Clay minerals are divided into four major groups: kaolinite, montmorillonite/smectite, illite and chlorite groups. The compositions of clay minerals depend on geographic area and the bedrock, and vary a lot all over the world. Clay soils have high plasticity index. According to Arora (2006), LL (liquid limit) is the water content at which the soil changes from liquid state to plastic state, while the PL (plastic limit), is the water content at which the soil changes from plastic state to semi-solid state. PI (plasticity index) is the numerical difference between the liquid limit and the plastic limit expressed as: PI = (LL â&#x20AC;&#x201C; PL). Soils with high PI indicate the presence of high proportion of clay fraction, while soils with lower PI tend to be silt. 2.3 Characterization of RH (Rice Husk) and RHA (Rice Husk Ash) RH (rice husk) is a by-product of the rice mill industry [8-10]. By weight, 10% of the rice grain is rice husk [11]. Jha and Gill [10] in their experimental study observed that for every 4 tons of rice, 1 ton is the rice husk. Similar study carried out by Alhassan [9], revealed that about 108 tons of rice hush is generated annually in the world. In Nigeria, about 2 million tons of rice are produced annually, while in Niger state alone, about 96,600 tons of rice grains are produced annually [12]. The husk generated from these will be enormous and is usually disposed carelessly by dumping in an open heap near the mill site or along the roadside where they are burnt. An analysis of RH as given by Muthadhi et al. [13], is shown in Table 1.

The ash is obtained from burning the rice husk. When the husk is burnt, about 15%-20% turns into the ash. The ash, being so light, is carried away by wind and water in its dry state. It is difficult to coagulate and thus contributes to air and water pollution. The cumulative generation of the ash from rice requires a large space for disposal and so its utilization and the exploitation of its inherent properties provide a perfect way to mitigate the associated environmental problems. Researchers have found that this ash has high percentage of siliceous materials and so has potential pozzolanic properties [14]. According to Houstin [1], it has been classified into high carbon char, low carbon ash and carbon free ash. The properties depend on whether it has undergone complete destructive combustion or is partially burnt. Meanwhile, it has been categorized under pozzolana with about 67%-70% silica, 4.9% aluminum and 0.95% iron oxides [12]. 2.4 Sample Preparation and Experimental Program Soils from Eke Obinagu Borrow Pit, Emene, Enugu State, Egbede Borrow Pit, Aba, Abia State and Ugwuaji, Nkanu, Enugu State were used for this study, while the Rice Husk was sourced from Abakaliki in Ebonyi State, barely 75 km from Enugu. Only the CBR and OMC, were considered. The second degree polynomial was used to model their behavior and the effects on the soil properties. On collection of the soil samples, they were first classified as given in Table 2, using BS 1377 standard Table 1

Typical analysis of rice husk [13].

Properties Bulk density (kg/m3) Length of husks (mm) Hardness (Mohrâ&#x20AC;&#x2122;s Scale) Ash (%) Carbon (%) Hydrogen (%) Oxygen (%) Nitrogen (%) Sulphur Moisture

Range 96-160 2-5 5-6 22-29 35 4-5 31-37 0.23-0.32 0.04-0.08 8-9

Models and Optimization of Rice Husk Ash-Clay Soil Stabilization Table 2 No. 1 2 3

Soil sample classification before stabilization. Properties Eke Obinagu Egbede Ugwuaji

BS 1377 Classification A-7-5 A-6 A-2-7

Source: Field work.

classification method. After classification the engineering properties of the soil were determined in accordance with BS1377 and 1990b, and presented in Table 3, while the chemical properties of the rice husk ash were presented in Table 4. The LL (liquid limits) of Eke Obinagu, Egbede and Ugwuaji were 61%, 40% and 49% before stabilization while their PI (plasticity index) were 35%, 17% and 18%, respectively. These results indicate that Eke Obinagu soil with high PI can expand and shrink in response to wet and dry seasons of the year more than the rest of the soils. Other properties are as shown in Table 3. The burning and preparation of the ash was carried out in a cylindrical incinerator. The CBR test was carried out on the materials after stabilization. The moisture content of the soil generally represents the design conditions for which the test results were derived and this was also examined.

3. Results, Discussions and Modeling Before stabilization the CBR value of Eke Obinagu (A-7-5) sample was 5% and thereafter rose to 29% at optimal stabilization of 17.5%. For Egbede (A-6) sample the CBR value was 7% before and 13% after, while it was 5% and 23% before and after respectively for Ugwuaji soil at 17.5% stabilization. The CBR plot in Fig. 1 showed that not all the three samples met the sub-grade requirement. According to Nigerian Roads and Bridges specification [15], the CBR value of sub-grade should be up to 15% or more after soaking for 48 h. Since the aim of this study is to know the soils that can respond favorably to stabilization with the ash, it was discovered that Eke Obinagu soil (A-7-5) with a CBR value of 29% responds

Table 3

1263

Engineering properties of the soil. Location

S/No Properties

Eke Obinagu OMC (%) 15 MDD (gkm3) 1.72 Soaked CBR (%) 5.00 Liquid limit (%) 61 Plasticity index (%) 35 % passing B.S. 65 Sieve size 63 mm Soil classification A-7-5

1 2 3 4 5 6 7

Egbede

Ugwuaji

14 1.97 6.00 40 17

15 1.88 5.00 49 18

A-6

A-2-7

Source: Field work. Table 4

Chemical properties of the RHA.

Compound composition SiO2 CaO MgO Fe2O3 Al2O3 Na2O K2O

Rice husk ash at 400 oC (%) 86.56 2.97 2.14 0.63 3.65 2.701 1.251

RHA obtained from open air (%) 89.15 2.10 1.32 0.18 4.32 1.48 1.399

Source: Field work.

better than the other two soils. However in all the soil samples the addition of ash resulted in increase in the CBR values. The models shall be obtained based on Sheffe’s model given as: p

E ( y ) = βo + ∑ βi x 2i + ∑ i=1

∑ βij x i x j +......+Є (1) i< j

which is the equation of independent variables for 2nd degree polynomial, where p is the number of components in the mixture. It is worthy of note that interests among researchers have changed from determining which process variables affect the response, to determining the region or important factors that lead to the best possible response [16]. Response surface methodology RSM is a collection of mathematical and statistical techniques useful for the analysis and modeling of problems in which a response of interest is influenced by several variables and the objective is to optimize this response [16-18]. RSM methods lead to product OPTIMIZATION

1264

Models and Optimization of Rice Husk Ash-Clay Soil Stabilization

variable is x2, the number of components in the

homogenous equations for the model coefficients are as follows using Eke Obinagu soil sample: Table 6 is generated for all the locations:

mixture is, p = 2. The constraint of Scheffe’s Model

Eke Obinagu CBR = 14.6469x1 + 0.05x2 – 0.1487x1 x2 (5)

for a mixture design is that

Egbede CBR = 1.7559x1 + 0.0575x2 + 0.0257x1 x2 (6)

which is the main object of Scheffe's model. If the RHA variable is assumed to be x1, while the soil

x1 + x2 +

….

xp = 1

x1 + x2 = 1

(2)

Ugwuaji CBR = 7.6021x1 + 0.0464x2 – 0.0743x1 x2 (7)

E(y) =Ff = (β0 + β1 + β11) x1 + (β0 + β2 + β22) x2 + (β12 –

The above models can be verified using the optimum results of the stabilized soils given in Table 7. The results of both the experiments and the model values are compared as shown in Tables 8-10 and in Figs. 1-3. In all the soil types the addition of the stabilizing agent resulted in increase in CBR values, collaborated with the results of the models. The CBR curve for the model is linear while that of the experiment increased

β11 – β22) x1 x2 = μ1 x1 + μ2 x2 + μ2 x1 x2

(3)

Put in a compact form, p

F f=

∑

1<i < p

μi x i +∑

∑

1<i < j <q

(4)

μ ij xi x j

The result of the least square method is a system of linear equations with three unknown constants μ1, μ2, μ12, which will be determined for each of the soils obtained from the three locations. From Table 5 the least square is as shown in Table 6 and the Table 5

Results after stabilization (OMC, MDD, CBR).

SN RHA (%) 1 2 3 4 5 6 7 8 9

0.00 2.5 5.00 7.5 10.00 12.50 15.00 17.50 20.00

Ugwuaji Nkanu A-2-7 OMC (%) MDD (g/cm3) CBR (%) 15.00 1.88 5.0 15.00 1.86 5.0 17.00 1.82 7.0 18.00 1.78 9.00 20.00 1.68 15.0 23.00 1.58 17.00 29.00 1.49 22.00 31.00 1.44 23.00 30.00 1.40 18.00

Egbede Borrow PIT A-6 OMC (%) MDD (g/cm3) CBR (%) 14.00 1.97 6.00 14.00 1.94 7.00 14.00 1.90 9.00 15.00 1.80 10.00 15.00 1.62 11.00 22.00 1.50 11.0 23.00 1.44 13.00 25.00 1.33 12.00 27.00 1.28 9.00

Table 6

Controllable variables for optimum moisture content.

S/NO 1 2 3 4 5 6 Σ

X1 0.00 2.50 5.00 7.50 10.00 12.50 37.50

Table 7

CBR/OMC values (for 15%, 17% and 20% stabilization).

X2 100.00 97.50 95.00 92.50 90.00 87.50 562.50

S/No

RHA (%)

1 2 3

15.00 17.50 20.00

X1 X2 0.00 243.75 475.00 693.75 900.00 1,093.75 3,406.25

X12 0.00 6.25 25.00 56.25 100.00 156.25 343.75

Eke Obinagu A-7-5 OMC (%) CBR (%) 28.0 28.0 33.0 29.0 33.0 26.0

X22 10,000.00 9,506.25 9,025.00 8,556.25 8,100.00 7,656.25 52,843.75

X12 X2 0.00 609.38 2,375.00 5,203.13 9,000.00 13,671.88 30,859.38

Egbede A-6 OMC (%) CBR (%) 23.0 13.0 25.0 12.0 27.0 9.00

Eke-Obinagu A-7-5 OMC (%) MDD (g/cm3) CBR (%) 15.00 1.72 5.00 16.00 1.69 6.00 18.00 1.63 7.00 23.00 1.60 8.00 26.00 1.48 22.00 27.00 1.44 23.00 28.00 1.41 28.00 33.00 1.37 29.00 33.00 1.34 26.00

X1 X22

X12 X22

0.00 23,765.63 45,125.00 64,171.88 81,000.00 95,703.13 309,765.63

0.00 59,414.06 225,625.00 481,289.06 810,000.00 1,196,289.06 2,772,617.19

Ugwuaji A-2-7 OMC (%) CBR (%) 29.0 22.0 31.0 23.0 30.0 18.0

Models and Optimization of Rice Husk Ash-Clay Soil Stabilization Table 8

CBR values for the model and experimental results (Eke Obinagu).

S/No 1 2 3

RHA (%) 15.0 17.50 20.0

Table 9

Soil sample (%) 85.0 82.50 80.0

RHA (%) 15.0 17.50 20.0

Table 10

Soil sample % 85.0 82.50 80.0

RHA (%) 15.0 17.5 20.0

CBR experiment (%) 13.0 12.0 9.0

Soil sample (%) 85.0 82.5 80.0

A-7-5

OMC %

A-2-7

15 A-6

15 10

17.5

Experiment Model

5 0

0 15

A-6

Experiment Model

Fig. 3

1.6 A-7-5

MDD

A-6

A-7-5

A-2-7

Combined plot of OMC against RHA.

slightly and decreases linearly at 17.5% stabilization for the Ugwuaji. Decrease in CBR value when the agent is increased suggests that the lack of cementing properties is a disadvantage to its use as a stabilizer for expansive soils. For this reason, it should be used with lime-containing material or cement for soil improvement.

A-2-7

1.2

17.5 RHA (%)

RHA (%)

Combined plot of CBR against RHA.

1.4

A-2-7 A-7-5

A-2-7

A-7-5

A-6

CBR model (%) 34.36 45.76 59.02

A-6

A-7-5

CBR experiment (%) 22.0 23.0 18.0

CBR model (%) 11.3 11.12 10.6

7 A-2-

A-6

0.8 0.6 0.4

4. Conclusions

0.2

Experiment Model

0 15

17.5 RHA (%)

Fig. 2

CBR Model (%) 23.24 29.59 36.89

CBR values for the model and experimental results (Ugwuaji Sub-base).

S/No 1 2 3

CBR

CBR experiment (%) 28 29.0 26.0

CBR values for the model and experimental results (Egbede Sub-base).

S/No 1 2 3

Fig. 1

1265

Combined plot of MDD against RHA.

The results of the models closely correspond with the experimental results especially with A-7-5 and A-6 soils and so the models could be used to predict the Siolâ&#x20AC;&#x201D;RHA properties in the absence of

Models and Optimization of Rice Husk Ash-Clay Soil Stabilization

1266

experimental results. In all the soil types, the addition of the stabilizing agent resulted in increase in OMC and CBR values similar to results from other literatures on the subject. At 15% to 17.5% stabilization the soils attained their maximum CBR values although the A-6 soil had the lowest values. These behavioral changes were also observed in the results of the models but the pattern of improvement varies with the different soils. This study therefore recommends that thus: Although ash from rice is a good stabilizing agent for expansive soils it will require lime-containing material or cement to achieve better results, the empirical models developed could be used to predict the properties of the stabilized soil in the absence of experimental data for the A-7-5 and A-6 soils.

[6]

[7]

[8]

[9] [10]

[11]

[12]

References [1]

[2]

[3]

[4]

[5]

D.F. Houstin, Rice Chemistry and Technology, American Association of Cereal Chemistry, Inc., St. Paul, Minnesota, 1972, pp. 301-340. C.S. Prasas, K.N. Maiti, R. Venugopal, Effect of RHA in white wave composition, Ceramics International 27 (2000) 629. G.V.R.P. Raju, B.P.C. Sekhar, B.R.P. Kumar, G. Mariyana, Strength characteristics of expansive soils stabilized with lime and rice husk ash, in: Proceedings of the National Seminar on Road Transportation: Issues and Strategies, Patiala, 1998, p. 20. M. Ali, V. Sreenivasulu, An experimental study on the influence of rice husk ash and lime on properties of bentonite, in: Proceedings of the Indian Geotechnical Conference, India, 2004, p. 468. B.C. Chattopadhyay, T.K. Roy, Uses of soil as road material with different technologies for improvisation, in: Proceedings of the National Conference on Advances in

[13]

[14]

[15] [16] [17]

[18]

Road Transportation (ART), NIT Rourkela, 2005, p. 491. E.A. Basha, R. Hahim, H.B. Mahmud, A.S. Muntohar, Stabilization of residual soil with RHA and cement, Journal of Construction and Building Materials 19 (6) (2005) 448-553. S. Chandra, S. Kumar, R.K. Anand, Soil stabilization with rice husk ash and lime sludge, Journal of Indian Highways 33 (5) (2005) 87-98. J.K. Mitchell, Practical problems from surprising soil behavior, J. Geotechnical Engineering 112 (3) (1996) 255-289. M. Alhassan, Potential of rice husk ash for soil stabilization, AU Journal of Technology 11 (4) (2008) 246-250. J.N. Jha, K.S. Gill, Effect of rice husk ash on lime stabilization, Journal of the Institute of Engineering India, 87 (2006) 33-39. P.K. Mehta, Concrete Structure, Properties and Materials, Prentice-Hall Eagle-Wood Cliffs, New Jersey, 1986, pp. 256-289. E.B. Oyetola, M. Abdullahi, The use of rice husk ash in low-cost sandcrete block production, Leonardo Electronic Journal 8 (2006) 58-70. A.C. Muthadhi, R. Anitha, S. Kothandaraman, Rice husk ashâ&#x20AC;&#x201D;Properties and its uses, A Review IE (I) Journal 88 (2007) 50-56. D.J. Cook, R.P. Pama, S.A. Damer, Rice husk ash as a pozzolanic material, in: Proceeding of Conference on New Horizons in Construction Materials, Lehigh University, Lehigh, 1976. Specification Limits for Materials for Roads and Bridges, Federal Ministry of Works, Nigeria, 1997. D.C. Montgomery, Designs and Analysis of Experiments, 6th ed., John Wiley and Sons, New York, 2005. R.H. Myers, D.C. Montgomery, G.C. Vining, C.M. Borror, S.M. Kowalski, Response surface methodology: A retrospective and literature survey, Journal of Quality Technology 36 (2004) 53-77. R.H. Myers, D.C. Montgomery, A tutorial on generalized linear models, Journal of Quality Technology 29 (1997) 274-291.

Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1267-1278 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

DAVID

PUBLISHING

Gully Erosion Study and Control: A Case Study of Queen Ede Gully in Benin City Jacob O. Ehiorobo and Roland O. Ogirigbo Department of Civil Engineering, Faculty of Engineering, University of Benin, Benin 300283, Nigeria Abstract: This paper presents findings from studies carried out on the Queen Ede gully erosion site in Benin City, in the south-southern zone of Nigeria. The studies involved detailed topographical, geotechnical, meteorological and hydrological data acquisition. The data were processed and analyzed to determine catchment size, gully morphology, soil characteristics, rainfall pattern and hydrological pattern. These were then interpreted and used to determine the method of control to be adopted. The adopted control measures is a combination of structural and non-structural methods. The structural method involved the use of gully control structures to divert the runoff entering the gully from the head, while the non-structural method involved the use of boulders and vegetation to stabilize the gully walls around the head region. Key words: Queen Ede gully, gully erosion, catchment, control structures.

1. Introductionď&#x20AC; Gully erosion is an enormous type of environmental degradation which results in loss of valuable land used for agricultural, domestic, industrial and aesthetic purposes, as well as loss of property and even human lives [1]. It is formed as a result of water moving in rills, which concentrate to form larger channels. When rill erosion can no longer be repaired by merely tilling or disking, it is defined as gully erosion. Generally, gully erosion occurs when runoff concentrates and flows at a velocity sufficient to detach and transport soil particles. In Nigeria, high land use pressure particularly in the south-east and south-south regions render the landscape more vulnerable to gully erosion. Land use changes have also caused the development of bank gullies along some river banks [2]. A recent study conducted in the south-eastern parts of Nigeria, showed that the primary causes of gully erosion in this region is as a result of roads lacking Corresponding author: Jacob O. Ehiorobo, Ph.D., research fields: GNSS and geodetic positioning, deformation surveys and analysis, engineering and construction surveys and analysis, engineering and construction surveys, remote sensing, GIS, water resources modeling and environmental hazards analysis. E-mail: jeffa_geos@yahoo.com.

proper drainage, unguided cultivations, and indiscriminate channelling of flood water on sloped terrain [3]. Also, changes in drainage pattern associated with urbanization can give rise to the formation of gullies especially where illegal settlements exist. Gully erosion is the most destructive form of erosion as it destroys the soil structure, damage farm lands, destroy infrastructure, alter transportation corridors and lower water tables [4]. According to Ref. [5], the formation of gullies in the south-eastern part of Nigeria has become one of the greatest environmental disasters facing many towns and villages, as many agricultural lands have become unsuitable for cultivation and hundreds of people have had to relocate. Efforts are however being made to control some of these gullies as reported in Ref. [6]. A study conducted by Poesen [7] stated that soil shear strength at saturation of various soil horizons is a good indicator of their resistance against concentrated flow erosion. In Ezezika and Adetona [3], it was concluded that most of the gullies in the south-eastern part of Nigeria can be prevented from expanding by embarking on enhanced public awareness programs and better land management practices. While these

1268

Gully Erosion Study and Control: A Case Study of Queen Ede Gully in Benin City

practices can prevent the formation of future gullies, they are insufficient to control the huge gully erosion sites already existing. Apart from the south-eastern parts of Nigeria, gully erosion still plagues other areas like the south-southern regions where Edo state is located. In order to adequately address the problems associated with gully erosion in this region, proper studies would have to be carried out to determine the topographical, geological, geotechnical, meteorological and hydrological characteristics of gullies in the region. On the gullies in this region, very little research have been done on the state of the gullies, the processes involved and control measures (both temporary and long-term) that can be put in place to ensure that the growth of the gullies are investigated. It is to be noted that despite several case studies reported in literature, there is still the need for more research on the effectiveness and cost-efficiency of gully prevention and control measures. This is because, the effectiveness of many of these control measures depends on local conditions. For instance, it was reported that stabilizing a bank gully head in central Belgium with rock plug did not work in loess-derived soils and an alternative technique with geo-membranes had to be developed [8, 9]. This paper presents the findings from studies carried out on the Queen Ede gully erosion site in Benin City (south-south zone of Nigeria), and the solution adopted to prevent further growth and expansion of the gully by applying both structural and non-structural measures.

direction, covering a total land area of 59,250.099 m2, with a perimeter of 2,219 m. The study area lies within the tropical rain forest zone and is characterized by annual rainfall ranging from 1,558.1 mm in 2001 to 2,618.3 mm in 2010. The

2. Methodology

storm runoff coming towards the gully from the streets within the upland catchment area, but this resulted in creating a secondary gully at the gully head.

2.1 The Study Area The Queen Ede gully erosion site is located in Benin City, the capital city of Edo state in Nigeria. It lies within the UTM (Universal Traverse Mercator) zone 31 and is bounded by UTM coordinates 700,800 mN to 702,500 mN and 795,800 mE to 796,000 mE. The gully runs down to the Ikpoba River in a south eastern

elevation of the study area ranges from 16 m to 110 m above mean sea level. The location plan of the queen Ede gully erosion site in Benin City is shown in Fig. 1. 2.2 Causes of Gully Erosion Problem and Previous Efforts at Rehabilitation The Queen Ede gully is believed to have started sometime in the 1990s, as a result of the abrupt termination of the outlet drain from the Benin-Agbor highway around the current location of the gully. Additionally, the runoff for the steep slope from streets within the upland catchment area contributed largely to the formation of the gully. For instance, there are four 900 mm diameter culverts under the Benin-Agbor highway, which carry the storm discharge from the neighbouring streets located around the gully head to two catch pits located on the opposite side of the highway. An assessment of the catch pits indicated that they are inadequate in size compared to the volume of storm runoff they receive at a time and therefore they can not serve the purpose for which they were constructed. Efforts have been made in recent years by both the State and Federal Government to arrest the acceleration of the erosive action of the storm water in the area but these have not succeeded. Even recently, the local residents constructed a local earth channel to divert the

2.3 Field Survey Measurements Field reconnaissance survey was carried out using handheld Garmin 76 GPS, to capture key coordinates. Three control points were established at some distance on stable ground from the gully head by method of

Gully Erosion Study and Control: A Case Study of Queen Ede Gully in Benin City

1269

Fig. 1 Location of Queen Ede gully erosion site in Benin City.

Differential GPS. Leica Total Station instrument was then used for detailed surveys within the catchment basin to capture both the primary gully at Queen Ede and the other secondary gullies along Edebor and Pohgah streets.

Measurements were carried out to obtain the cross section of the gully and the topographical profile along the axis of the main gully channel from the head to the terminal point at Ikpoba River. Total station measurements were collected at 1 cm

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Gully Erosion Study and Control: A Case Study of Queen Ede Gully in Benin City

level resolution to capture break in slopes and other topographic features necessary for producing DEM (digital elevation models) and to determine various morphological parameters such as width, depth, volume of soil loss, etc.. High resolution Ikono Imagery was acquired for the study area in order to measure and monitor the extent

of the land area at risk, land use pattern, delineation of the catchment basin and analysis of infrastructure at risk or endangered by the gully. The topographical map of the Queen Ede gully erosion site is shown in Fig. 2. TIN (Triangulated Irregular Network) model of the gully site is shown in Fig. 3a while SPOT satellite image map of the site is shown in Fig. 3b.

Fig. 2 Topographical map of Queen Ede gully and its catchment basin.

Gully Erosion Study and Control: A Case Study of Queen Ede Gully in Benin City

(a)

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Gully Erosion Study and Control: A Case Study of Queen Ede Gully in Benin City

(b) Fig. 3 The gully: (a) TIN (triangulated irregular network) model of the gully; (b) Ikono imagery of gully.

2.4 Geotechnical Investigation Soil samples were collected from gully cross section along the bed and walls at specific locations and taken to the laboratory for testing and analysis. The tests carried out included natural moisture content, Atterberg limit tests, specific gravity tests, gradation, California Bearing Ratio tests, compaction tests, U-U triaxial and direct shear tests. 2.5 Hydrological Studies Nigeria receives rainfall from the south westerlies which invade the country from the Gulf of Guinea

Coast. The moist air stream is overlain by the north east trade wind which originates from the Sahara, which is dry and dusty. The zone where these two air masses meet is a zone of moisture discontinuity and it is referred to as the ITD (inter tropical discontinuity). The rainfall producing system for Nigeria is a function of the migration pattern of the ITD. Meteorological data have shown that the rainfall pattern in Nigeria have changed in the past decades, due to climate changes caused primarily by the effects of global warming. For example, the rainy season for the year 2012 began in late January, as against the usual periods of March and April. The monthly rainfall

Gully Erosion Study and Control: A Case Study of Queen Ede Gully in Benin City

distribution for 2001-2010 was obtained from Benin meteorological station. Using a design period of 2, 5, 10, 25, 50 and 100 years duration, respectively, IDF (intensity duration frequency) curves were prepared for the study area. Once the catchment basin has been delineated, rainfall intensity for the study area was computed using rainfall duration, equal to the time of concentration (TC), where,

. .

, in minute [1].

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both the gully bed and gully walls revealed that: • The soil’s specific gravity ranged from 2.37-2.66; • More than 37.69% of the samples passed through Sieve No. 0.075 mm; • Liquid limit ranged from 27.71%-3.55%, plasticity limit (10.39%-27.04%), plasticity index (13.11%-49.8%); • Maximum dry density ranged from 1.19-1.87 g/cm2; • Angle of internal friction, Ø = 15o and cohesion, C = 2 kN/m2;

3. Data Processing and Results

• CBR (California bearing ratio) values were very

Spot elevation along with points coordinates were obtained from the Total Station instrument using the in-built software of the instrument. Based on the points coordinates, morphological cross sections were obtained at 20 m interval. Other morphological parameters were calculated including length, width, depth and areas. The morphological parameters are shown in Tables 1 and 2. Using arc GIS 9.2 software, DEMs (digital elevation models) along with contours were plotted. This was then superimposed on the Ikono Imagery for catchment basin delineation and analysis. Also cross sections were plotted at 20 m interval and bed profile from the head to the point of discharge. These are shown in Fig. 4, Figs. 5a and 5b, respectively. The results of the soil tests from samples taken from

low (less than 5%) for both soaked and unsoaked. The monthly rainfall for 2001-2010 is presented in Table 3 and Fig. 6. Using Eq. (1), the time of concentration was computed to be equal to 34 min. This is the time required to move surface runoff from the remotest point of the catchment basin to its outlet. Rainfall Intensity Duration Curve was used estimate the effect of rain drop on gully wall and gully head erosion at the site (Table 3 and Fig. 6)

4. Analysis and Discussion From Tables 1 and 2, the maximum width of the gully as in January 2012 was 112 m and the minimum width was 15.6 m. The maximum depth was 16.4 m and the minimum depth was 0.4 m. The WDR (width to depth ratio) varied from 2 to 42. The volume of soil

Table 1 Morphological parameters of Queen Ede Gully as at January 2012. Chainage (m)

Top width, B (m) Depth, D (m)

BDR

Cross sectional area, A (m2)

Cumulative volume, V (m3)

00 + 000

15.604

0.374

3,510

0.000

00 + 100

101.218

9.155

431,335

25,544.340

00 + 200

74.184

12.394

709,756

77,353.480

00 + 300

31.752

8.432

213,881

118,422.800

00 + 400

56.205

8.981

381,768

144,309.500

00 + 500

70.000

16.378

841,278

227,958.000

00 + 600

112.000

13.409

970,039

314,372.000

00 + 700

17.363

9.854

128,751

344,273.800

2.5

00 + 800

19.365

7.780

127,897

354,944.560

00 + 900

77.226

3.890

196,260

368,975.840

00 + 960

40.815

4.480

85,271

393,069.580

00+00 00+20 00+40 00+60 00+80 00+100 00+120 00+140 00+160 00+180 00+200 00+220 00+240 00+260 00+280 00+300 00+320 00+340 00+360 00+380 00+400 00+420

Top width 2010 2011 DIFF 15.604 15.60 0.000 36.993 36.99 0.000 62.702 68.58 5.878 39.300 43.29 3.990 61.687 61.69 0.003 99.454 101.20 1.746 76.554 76.55 0.000 80.297 80.30 0.003 81.627 81.63 0.000 76.533 76.53 0.000 74.184 74.18 0.000 75.820 82.16 6.340 40.418 50.17 9.752 41.971 54.27 12.299 36.292 49.53 13.238 31.752 31.75 0.000 32.290 32.29 0.000 30.000 30.00 0.000 31.780 31.78 0.000 41.297 41.30 0.000 56.205 56.21 0.000 62.090 62.09 0.000

Bottom width 2010 2011 DIFF 10.000 10.000 0.000 13.466 13.466 0.000 28.556 28.920 0.364 29.873 30.002 0.129 17.500 17.500 0.000 81.556 82.877 1.321 65.996 65.996 0.000 66.556 66.556 0.000 69.246 69.246 0.000 71.784 71.784 0.000 60.000 60.000 0.000 60.870 60.000 -0.870 32.232 32.232 0.000 37.500 38.060 0.560 22.500 22.500 0.000 18.026 18.026 0.000 22.098 22.098 0.000 23.894 23.894 0.000 19.505 19.505 0.000 30.705 30.705 0.000 40.841 40.841 0.000 46.441 46.441 0.000 2010 0.374 3.478 4.751 9.889 7.846 9.155 6.988 13.788 10.585 7.112 12.394 13.007 10.727 7.492 7.208 8.432 8.855 7.975 7.046 8.737 8.981 10.306

Table 2 Morphological parameters of Queen Ede for 2010-2011. Depth 2011 0.374 3.478 4.751 9.889 7.846 9.155 6.988 13.788 10.585 7.112 12.394 13.007 10.727 7.492 7.208 8.432 8.855 7.975 7.046 8.737 8.981 10.306 DIFF 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

Cross-section area 2010 2011 DIFF 3.510 3.510 0.000 55.172 55.172 0.000 173.467 176.780 3.313 242.322 247.670 5.348 316.256 316.256 0.000 429.739 431.335 1.596 328.321 328.321 0.000 726.142 726.142 0.000 593.031 593.031 0.000 283.207 283.207 0.000 709.756 709.756 0.000 897.077 914.951 17.874 357.197 386.809 29.612 288.332 313.481 25.149 204.210 224.344 20.134 213.881 213.881 0.000 220.372 220.372 0.000 218.855 218.855 0.000 179.625 179.625 0.000 283.715 283.715 0.000 391.768 391.768 0.000 499.879 499.879 0.000 0.000 1,103.440 3,469.340 4,846.440 6,325.120 8,594.780 6,566.420 14,522.840 11,860.620 5,664.140 14,195.120 17,941.540 7,143.940 5,766.640 4,048.200 4,277.620 4,407.440 4,377.100 3,592.500 5,674.300 7,835.360 9,997.580

2010

Volume 2011 0.000 1,103.440 3,535.600 4,953.480 6,325.120 8,626.700 6,566.420 14,522.840 11,860.620 5,664.140 14,195.120 18,299.020 7,736.180 6,269.620 4,486.880 4,277.620 4,407.440 4,377.100 3,592.500 5,674.300 7,835.360 9,997.580 DIFF 0.000 0.000 66.260 107.040 0.000 31.920 0.000 0.000 0.000 0.000 0.000 357.480 592.240 502.980 402.680 0.000 0.000 0.000 0.000 0.000 0.000 0.000

Cum volume of soil loss 2011 DIFF 0.000 0.000 0.000 1,103.440 1,103.440 0.000 4,572.780 4,639.040 66.260 9,419.220 9,592.520 173.300 15,744.340 15,917.640 173.300 24,339.120 24,544.340 205.220 30,905.540 31,110.760 205.220 45,428.380 45,633.600 205.220 57,289.000 57,494.220 205.220 62,953.140 63,158.360 205.220 77,148.260 77,353.480 205.220 95,089.800 95,652.500 562.700 102,233.740 103,388.680 1,154.940 108,000.380 109,653.300 1,657.920 112,084.580 114,145.180 2,060.600 116,362.600 118,422.800 2,060.200 120,769.600 122,830.240 2,060.640 125,146.740 127,207.340 2,060.600 128,739.240 130,799.840 2,060.600 134,413.540 136,474.140 2,060.600 142,248.900 144,309.500 2,060.600 152,246.480 154,307.080 2,060.600 2010

Chhainage (m)

(b) Fig. 5 Gullyy bed profile: (aa) 0 m to 560 m; m (b) 560 m too 960 m. 0+540 44.537 0+560 44.202

0+520 42.504

0+500 44.284

0+480 44.284

0+460 45.364

0+440 46.104

0+420 46.407

0+400 45.714

0+380 44.039

0+960 36.576

0+360 46.404

0+920 37.196

0+340 46.689

0+900 37.611

0+940 36.891

0+300 47.239

0+280 47.948

0+260 48.006

48 210 0+240 48.210

0+220 48.666

0+200 49.996

0+180 55.916

0+160 56.736

0+140 56.126

0+120 58.564

0+100 60.861

0+320 46.809

0.017%

0+880 37.971

(a)

0+860 38.321

0+840 38.591

69.52

0+60 63 468 0+80 63.468

73.24

0+40

75.158

76 532 76.532 G bed levels (m) Gully

0+820 39.031

0+800 39.381

0+780 39.416

Bed slope (%) Gully bed levels (m) G

0+760 39.996

0+740 40.511

0+720 40.671

0+700 41.426

0+680 41.341

0+660 41.864

0+640 39.266

0+620 42.284

0+600 42.719

0+20

0+00 Chhainage (m)

0+580 43.514

0+560 44.202

Gully Ero osion Study and a Control: A Case Study of Queen E Ede Gully in B Benin City 12755

m 200 m, 400 m, 600 m and 800 m. Fig. 4 Crosss sections at 0 m,

B slope (%) Bed

0.017%

Year 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Total Mean Max Min

Jan. 0.00 0.00 0.00 0.00 61.60 12.80 7.50 0.00 5.60 3.20 90.70 9.07 61.60 0.00

Feb. 14.60 16.00 9.70 18.80 44.40 49.40 51.10 38.90 40.60 37.70 321.20 32.12 51.10 9.70

Mar. 111.40 165.40 78.70 97.60 110.40 157.50 108.90 42.40 148.20 109.40 1,129.90 113.00 165.40 42.40

Apr. 181.77 196.50 200.80 267.30 115.20 136.50 259.70 211.40 106.30 386.30 2,061.70 206.17 386.20 106.30

May 273.80 222.60 189.20 323.50 266.00 137.70 298.30 182.40 178.40 368.30 2,440.20 244.02 368.30 137.70

Jun. 202.00 351.40 272.10 388.40 308.20 352.70 351.70 385.30 250.20 277.70 3,139.70 313.97 388.40 202.00

Jul. Aug. Sep. 224.30 65.70 296.90 489.10 140.40 148.30 515.90 149.20 300.70 359.10 128.40 383.40 294.70 191.30 379.40 569.20 127.10 393.00 445.30 82.40 402.80 434.80 275.30 410.70 174.30 722.40 369.10 506.10 257.10 336.70 4,012.80 2,139.30 3,421.00 401.28 213.93 342.10 569.20 275.30 410.70 174.30 65.70 148.30

Table 3 Monthly rainfall distribution for Benin City from 2001-2010, in mm. Oct. 147.80 111.40 241.10 128.10 236.20 150.30 292.20 384.20 291.70 138.40 2,121.40 212.14 384.20 111.40

Nov. 39.90 108.40 162.30 70.80 124.70 23.30 39.90 29.80 154.80 102.10 860.00 86.00 162.30 23.30

Dec. 0.00 12.90 0.00 4.90 0.00 22.80 11.50 0.00 1.10 91.30 145.00 14.50 91.30 0.00

Total Mean 1,558.10 129.84 1,962.40 163.53 2,119.70 176.64 2,170.30 180.86 2,132.10 177.68 2,132.30 177.69 2,351.30 195.94 2,395.20 199.60 2,442.40 203.53 2,618.30 218.19 21,882.00 1,823.50 2,188.20 182.35

Max 273.80 489.10 300.70 388.40 379.40 569.20 445.30 434.80 722.40 386.30 4,389.00 438.90

Min 0.00 0.00 0.00 0.00 0.00 12.80 7.50 0.00 1.10 3.20 37.50 3.75

Gully Ero osion Study and a Control: A Case Study of Queen Ede E Gully in B Benin City

12777

Fig. 6 Rainffall IDF (intenssity duration frrequency) curvve for Benin City. C

Fig. 7 Slope stabilization technique. t

loss was estiimated to be 393,069.580 3 m3 over a surrface area of 126,4480 m2 whichh is equivalennt to 3.108 m3/m2. Recent results (Table 1) 1 showed thaat under—cuttting and collapsee of gully waalls continue to occur aroound the gully heaad as a result of active erossive action inn this area caused by the storm runoff. The geoteechnical inveestigation resuults revealed that the soil is silty s clay. Errosion in this type of sooil is irreversible and a it is reasoonable to assuume that theree is a tendency for widening of o gully to occur due to wall slumping esppecially durinng the periodd characterized by high rainfalll (from May-S September). Arising froom the above, the followingg control meassures

werre proposed foor the Queen E Ede gully erossion:  Redesign and a provide aadequate draiinage system m thatt will be ablee to carry all tthe storm run noff from thee catcchment area, and channel them away frrom the gullyy to appropriate a diischarge poinnts;  Implement appropriaate reclam mation andd stab bilization of the t gully heaad to prevent further headd cuttting;  Provide cheeck dams alonng the gully bed b to controll mov vement and transportatiion of erod ded soils byy redu ucing high runoff r and fflow velocitiees along thee gullly bed and thhereby protectting the bed from f incisionn and d deepening;

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Gully Erosion Study and Control: A Case Study of Queen Ede Gully in Benin City

 Provide adequate slope stabilization along the gully walls using gabions as retaining walls at the base and rock boulders placed on the gully walls, which have been trimmed to appropriate slopes. In between these boulders are planted vetiver grass and bamboo trees with firm roots to hold the soil in place against erosion. The boulders are held down by steel meshes, which will later be removed as the grasses and trees begin to grow. Typical cross section of the proposed method is shown in Fig. 7.

gully bed, can be used to prevent the gully from expanding.

References [1]

[2]

5. Conclusions [3]

Based on the findings from the studies conducted, the following conclusions were drawn:  The likely cause of this gully is as a result of the river bank eating back into the land, and this has been accelerated by the way the accumulated runoff from the catchment enters into the river;  The recent abrupt growth and expansion of the gully can be attributed to the change in the rainfall pattern in the region, which has been caused by climate change resulting from global warming;  Apart from the head region of the gully, other regions such as the middle and the tail regions have already stabilized. Thus, only the head region is active;  The results from the geotechnical studies conducted on the soil showed that the soil is susceptible to water erosion;  The existing drainage facilities are inadequate to contain the runoff coming from the catchment;  Control measures such as slope stabilization for the gully walls around the head region, redesigning and upgrading of the existing drainage system, provision of gully control structures at the head region, and provision of check dams at specific intervals along the

[4] [5]

[6]

[7]

[8]

[9]

I.I. Obiadi, C.M. Nwosu, N.E. Ajaegwu, E.K. Anakwuba, N.E. Onuigbo, E.O. Akponomu, et al., Gully erosion in Anambra State, south east Nigeria: Issues and solution, International Journal of Environmental Sciences 2 (2) (2011) 795-804. J.O. Ehiorobo, O.C. Izinyon, Measurement and documentation for flood and erosion monitoring and control in the Niger Delta States of Nigeria, www.fig.net/pub/fig2011 (accessed Jan. 1, 2013). O.C. Ezezika, O. Adetona, Resolving the gully erosion problem in south-eastern Nigeria: Innovation through public awareness and community-based approaches, Journal of Soil Science and Environmental Management 2 (10) (2011) 286-291. C. Valentin, J. Poesen, L. Young, Gully erosion: Impacts, factors and control, Catena 63 (2005) 132-153. K.O. Adekalu, I.A. Olorunfemi, J.A. Osunbitan, Grass mulching effect on infiltration, surface runoff and soil loss of three agricultural soils in Nigeria, Bioresource Technology 98 (4) (2007) 912-917. S.C. Teme, P.O. Youdeowei, Geotechnical investigations for design of foundations for erosion and flood control structures at Unwana Beach, Afikpo, Ebonyi state, South-Eastern Nigeria, in: Proceedings of 5th International Conference on Case Histories in Geotechnical Engineering, New York, USA, Apr. 13-17, 2004. J. Poesen, Gully topology and gully control measures in the European loess belt, in: S. Wicherek (Ed.), Farm Land Erosion in Temperate Plains and Hills, Elsevier, Amsterdam, 1993, pp. 221-239. J. Poessen, J. Ngchtergaele, G. Verstraeten, C. Valentin, Gully erosion and environmental change: Importance and research needs, Catena 50 (2003) 91-133. G. Verstraeten, J. Poesen, The nature of small-scale flooding, muddy floods and retention pond sedimentation in central Belgium, Geomorphology 29 (1999) 275-292.

Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1279-1286 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

DAVID

PUBLISHING

Analysis of the Antenna’s Setup Errors at the Global Navigation Satellite System Measurements Evangelia Lambrou School of Rural and Surveying Engineering, National Technical University of Athens, Athens 15780, Greece Abstract: Today, the GNSS (global navigation satellite system) is used for more complicate and accurate applications such as monitoring or stake out works. The truth lies in the fact that in the most of the times not enough attention is paid to the antenna’s setup. Usually, gross errors are found in the antenna’s centering, leveling and in the measurement of its height, which are significant. In this paper, a thoroughly analysis of the above mentioned errors is carried out. The influence of these errors in the calculation of the X, Y, Z Cartesian geocentric coordinates and the φ, λ, h ellipsoid geodetic coordinates of a point P on the earth’s surface, is analyzed and is presented in several diagrams. Also a new convenient method for the accurate measurement of the antenna’s height is presented and it is strongly proposed. The conclusions outline the magnitude of these errors and prove the significance of the antenna’s proper setup at the accurate GNSS applications.

Key words: GNSS antenna’s height, centering and leveling errors, GNSS antenna’s setup.

1. Introduction The GNSS (global navigation satellite system) measurements are used for the determination of accurate coordinates of points (of the order of some mm), which belong to monitoring networks, or to stake out applications [1-3]. It is well known that the human intervention during the measurements is minimum by using the satellite positioning systems. Namely no sighting is needed, as when total stations are used. However, a receiver must be put at a selected point, the antenna must be centered and leveled properly and the antenna’s height must be measured by using a usually simple tape. Are all the above-mentioned activities carried out with the proper manner? Mistakes, gross or random Corresponding author: Evangelia Lambrou, assistant professor, research fields: development of methodology for the determination of astronomical coordinates, precise determination of undulation n of geoid, interconnected systems, e-geodesy, observations via internet, check and calibration of geodetic instruments (geodetic metrology), development of methodologies for precise measurements, geometric documentation of technical and natural structures. E-mail: litsal@central.ntua.gr.

errors, which could be done, when a GNSS antenna placed will be proved significant. Today the minimum uncertainties, which are expected, require major attention to the measurement of antenna’s height and to the antenna’s centering and leveling in order to acquire correct measurements. In the following paragraphs, the aforementioned errors are analyzed, in order to determine the magnitude of the error that each one adds in the calculation of the geodetic coordinates φ, λ and h or the geocentric coordinates X, Y, Z of a point. As the errors that will be discussed are of the order of some centimeters, it may be considered that the earth is a solid sphere with radius R. This admission is adequate for the analysis.

2. The Antenna’s Height As the ellipsoid is the reference surface of the GNSS system, is useful to remind that the height of the antenna (ah) is measured along the plumb line instead of the geodetic normal as ought to be measured (Fig. 1). Eq. (1) gives the correct antenna’s height:

Analysis of the Antenna’s Setup Errors at the Global Navigation Satellite System Measurements

1280

d i o s p i l l e e h t o t l a c i t r e v

' P

r e t n e c e s a h p s ' a n n e t n a

Assuming that the error of the antenna’s height measurement is e, then the coordinates of point P will

εε

be: e n i l p m u l p

X p  X p '  ( a h  e)  cos   cos 

(4)

Y p  Y p '  (a h  e)  cos   sin  Z p  Z p '  (a h  e)  sin 

The errors m X p , mY p , mZ p , that correspond to the

d i o e G

coordinates XP, YP, ZP, due to the error e are as follows: m X p   e  cos   cos 

(5)

d i o s p i l l E

mY p   e  cos   sin  m Z p   e  sin 

Fig. 1 The measurement of the antenna’s height along the plumb line.

(1)

a h  a h ( measured )  cos 

where, ε is the deviation of the vertical, at the specific point. As the deviation of the vertical (ε) is of about some arcsec and a mean antenna’s height is of about 1.5 m, it’s obvious that this correction is insignificant. Thus, when the coordinates of a point P on the earth’s surface, (XP, YP, ZP) are needed the coordinates at a point P´, (XP, YP, ZP) (Fig. 1) are initially calculated. The point P´ corresponds to the electric phase center of the antenna.

The magnitude of each component depends on the position of the point P on the earth’s surface, namely, its approximate latitude and longitude. It is noted that, this error does not influence the ellipsoid coordinates φ, λ of point P but only the geometric height h, which bears the total error. Figs. 2-4 illustrate the change of the components m X p , mY p , mZ p , for an error e equal to 1 cm in relation

to the position φ, λ of the point P on the earth’s surface. As it is depicted in the diagrams, m X and mY p

transformation of φ, λ coordinates to X, Y, Z [4] but

fluctuate from 0 mm to 10 mm. Their absolute values are minimized at φ = ± 90o at the earth’s poles and they are maximized near the equator. Also m X decreases, when λ increases as mY rises. On the contrary mZ , becomes 0 at the equator and it

simplify them considering that the earth is a sphere

maximizes at the poles.

Using

the

fundamental

equations

for

the

with radius R, then the coordinates of the point P´ can be calculated: X p '  ( R  h p ' )  cos   cos  Y p '  ( R  h p ' )  cos   sin 

(2)

Z p '  ( R  h p ' )  sin 

3. Accurate Measurement of the Antenna’s Height The measurement of the antenna’s height using a tape, while it is on a tripod or a pillar is not an

It is pointed out that the geometric height h of P´ includes the antenna’s height measurement ah: h p'  h p  ah

accurate procedure. So, some manufacturer are accompanied their receivers with a special equipment

(3)

for the antenna’s height measurements [5]. Also

Namely, the component of the antenna’s height ah

guidelines are given for the proper measurement of an

in relation to the geocentric coordinate system X, Y, Z

antenna’s height [6, 7].

ought to be subtracted from the coordinates XP, YP,

A mistake of some millimeters or a little more can

ZP in order to the desired coordinates XP, YP, ZP of the point P be calculated by combining Eqs. (2) and (3).

be very easily read. Additionally, the proper positioning of the tape on the antenna’s hook or on the

Analysis of the Antenna’s Setup Errors at the Global Navigation Satellite System Measurements

10 8 6

mXp(mm)

4 2 0 -2 -4 -6 -8 -10 -90

-80 -70

-60

-50 -40

-30

-20

-10

Geodetic Latitude (o )

Fig. 2

λ=0

λ=30&330

λ=60&300

λ=120&240

λ=150&210

λ=180

λ=90&270

The error m X p for e = 1 cm. 10 8 6

mYp (mm)

4 2 0 -2 -4 -6 -8 -10 -90

-80 -70

-60

-50 -40

-30

-20

-10

Geodetic Latitude (o )

Fig. 3

λ=0&180

λ=30&150

λ=60&120

λ=210&330

λ=240&310

λ=270

λ=90

The error mY p for e = 1 cm. 10 8 6

mZp (mm)

4 2 0 -2 -4 -6 -8 -10 -90

-80

-70

-60

-50

-40

-30

-20

-10

Geodetic Latitude (o )

Fig. 4

The error m Z p for e = 1 cm.

1281

1282

Analysis of the Antenna’s Setup Errors at the Global Navigation Satellite System Measurements

antenna’s band or on the antenna’s bumper is doubtful. Moreover, the zero point of the tape, most of the times, is not in the proper position. Finally, the misreading of the tape must be taken into consideration as a gross error. Therefore, for special GNSS applications which need the maximum accuracy, it is proposed that the measurement of the antenna’s height should be carried out by using the spirit leveling method as follows: (1) Before the antenna’s setup at a selected point P, it is essential for a staff to be put on it (Fig. 5a); (2) A digital level is placed and is leveled at a close distance of about 3-5 m. The indication i on the staff is then registered; (3) Next, the tripod with the tribrach and the adaptation base of the antenna is placed, centered and leveled at point P; (4) The staff is put on the surface of the adaptation base where the antenna will be mounted, and a second indication j is registered (Fig. 5b). The antenna’s height ah is calculated easily by the equation: (6) ah  i  j By using the above procedure, the true vertical measurement of the antenna’s height ah from the bottom of its mount is calculated. It is also indicative that the distance d between the antenna’s electric phase center and the bottom of the antenna’s mount, is accurately known (md = ± 0.1 mm) as it is given by the manufacturers in order to be used in the process of calculating the measurements. The accuracy that i and j can be measured is of the order of mi = mj = ± 0.1 mm by using a system digital level—barcode staff. Thus, applying the variance covariance low in Eq. (6), the total uncertainty of an antenna’s height measurement is determined by: mah 

m m 2 i

2 j

  0 . 15 mm   0 . 2 mm

4. The Centering and Leveling Errors The centering error is defined as the deviation of the projection along the plumb line of the antenna’s phase center from the desire point P (Fig. 6). In correspondence to the centering error, the leveling error has the same definition due to the wrong leveling of the antenna. Moreover, in this case, the measurement of the antenna’s height holds an additional error. These errors present the deviation of the main vertical axis of the antenna, from the plumb line, which intersects the desire point P. Despite the human carelessness during the set up of the antenna, these errors are also caused either due to a tribrach bad check or to a complete overlook of a required check. The antenna’s centering and leveling errors both exist on a horizontal plane, which is perpendicular to the plumb line at point P. Both are gross errors and it is difficult to discover and define the true vector, which represent them. The result of these errors is a vector PP with an unknown absolute value. This vector ecl (Fig. 6) starts from the desired point P and has a random geodetic azimuth A. Considering that the earth is a solid sphere with a mean radius R = 6,371 km then this vector can be analyzed in two components, one along the meridian, namely σφ, and the other along the parallel, namely σλ. The components σφ and σλ, as presented in Fig. 6, are:   (m)  ecl  cos A

  (m)  ecl  sin A

 ecl  cos A    '' R  

(8)

 ecl  sin A     ' '  R  cos  

(9)

  ''  

  ''  

where, (7)

The above analyzed procedure proved easy to apply and extremely accurate as it required less than 5 min to be implemented and protects against gross or systematic tape-reading errors.

A is geodetic azimuth of the vector PP(ecl); ecl is absolute value of the error; ρ´´ is 206,265. The σφ fluctuates from ecl, if A = 0 or A = π, to zero if A = π/2 or A = 3π/2. The opposite is valid for σλ.

Analysis of the Antenna’s Setup Errors at the Global Navigation Satellite System Measurements

(a)

1283

(b)

Level

i P

Centering point



point's meridien

Fig. 5

Centering point The accurate measurement of an antenna’s height.

 

ecl 

r o t a u q E



σφ σφ σλ σλ

σφ

` ` P

P''

σλ

Fig. 6

The analysis of the vector of centering and leveling error.

As previously mentioned, it is difficult to determine

m2 

the azimuth A of this vector which varies from 0 to 2π. Thus the mean value m of this error ecl (centering and leveling) along the meridian according to the Eq. (8) m2 

 (e

 cos A) n

m2 

(10)

where, n is the elementary step dA of azimuth A from 0 to 2π. 2 n dA

(11)

According to Eq. (11) the following integral can be formed:

 (e

 cos A) 2 dA

(12)

By solving the integral of Eq. (12), the following result comes out:

can be calculated as: 2

2

1 2

2

1 2

2

 (e

 cos A) 2 dA 

2

1 2 1 2 cos 2 A  ecl   cos 2 AdA   ecl   dA 2 2  2 0 0 

2 2  e2 1 2 1 1  ecl    dA   cos 2 AdA  cl 2 2 0 2 0  2

(13)

The same result arises if Eq. (9) used for the calculation of the mean error along the parallel. Thus a mean value of centering and leveling error is

Analysis of the Antenna’s Setup Errors at the Global Navigation Satellite System Measurements

1284

equal to:

coordinates at point P. It is pointed out that σλ does e m   cl 2

(14)

not add error to the Z coordinate of point P. Also the accurate value hP is insignificant compared to the

The following chart (Fig. 7) depicts the mean error at φ and λ due to an error ecl of the antenna’s centering and leveling. This error can also be analyzed in the geocentric coordinates system according to the Eq. (2). It adds an error mcl in the geocentric coordinates XP, YP, ZP of the desired point P as follows:

earth’s radius for the calculation of the errors mcl by using Eq. (15). Figs. 8 and 9 illustrate the mclXp , mclYp , for an error σφ = σλ =1 cm ≈ 0´´.0003 for all combinations of φ and λ, assuming that hP = 0.

mclXp  ( R  h p )  cos   cos   cos(    )  cos(     ) 

Fig. 10 illustrates the mclZp for an error σφ = σλ = 1 cm ≈ 0´´.0003 and σφ = σλ = 5 cm ≈ 0´´.0015, for

mclYp  ( R  h p )  cos   sin   cos(    )  sin(     ) 

mclZp  ( R  h p )  sin   sin(    ) 

(15)

all combinations of φ and λ, assuming that hP = 0. Figs. 8 and 9 look like nomograms as they are

Consequently, mclXp, mclYp , mclZp , are the corrections that should be applied to the calculated geocentric

enough complicated. The error mcl takes zero value as well as the maximum value 10 mm, for every

coordinates at P in order to achieve the correct

longitude but for different latitudes.

Mean error in φ m) Mean error in φ,,λ (m λ (mm)

45 40 35 30 25 20 15 10 5 0 0

e cl (mm)

Fig. 7

The mean error at φ and λ in mm. 12 10 8 6 mclXp (mm)

4 2 0 -2 -4 -6 -8 -10 -12 -90

-80

-70

-60

-50

-40

-30

-20

-10

Geodetic Latitude (o )

Fig. 8

λ=0

λ=30

λ=60

λ=90

λ=120

λ=150

λ=180

λ=210

λ=240

λ=270

λ=300

λ=330

The mclXp for an error σφ = σλ = 1 cm ≈ 0´´.0003.

Analysis of the Antenna’s Setup Errors at the Global Navigation Satellite System Measurements

1285

12 10 8 6 mclYp (mm)

4 2 0 -2 -4 -6 -8 -10 -12 -90 -80 -70

-60 -50 -40 -30 -20 -10

Geodetic Latitude (o )

Fig. 9

λ=0

λ=30

λ=60

λ=90

λ=120

λ=150

λ=180

λ=210

λ=240

λ=270

λ=300

λ=330

The mclYp for an error σφ = σλ =1 cm ≈ 0˝.0003. 0 -5 -10 -15 mclZp(mm)

-20 -25 -30 -35 -40 -45 -50 -55 -90 -80 -70 -60 -50 -40 -30 -20 -10

Geodetic Latitude (o ) mcl=1cm

Fig. 10

mcl=5cm

The mclZp for an error σφ = σλ = 1 cm ≈ 0˝.0003 and σφ = σλ = 5 cm ≈ 0˝.0015.

5. Conclusions The inaccuracies of the antenna’s setup are disregarded, as no works on this subject were carried out worldwide. Nevertheless, it is proven by the aforementioned analysis, that significant error may change the final coordinates, which are calculated by the GNSS systems. An error in the antenna’s setup, affects the geocentric coordinates X, Y, Z, the ellipsoid coordinates φ, λ, and the h of a point P. The transmitted error e in the measurement of the antenna’s height at the X, Y, Z geocentric coordinates depends on the position of the point on the earth’s

surface, namely its latitude and longitude. So, this error in each coordinate fluctuates from 0 to the maximum value e. The error in the measurement of an antenna’s height does not affect the φ, λ coordinates but only the geometric height h of the point. To avoid this error, a special prototype procedure for the measurement of antenna’s height is proposed in order to eliminate this error to ± 0.2 mm. This method is efficient, accurate and easy to perform. It is evaluated as worthy, despite the fact that more instrumentation is needed. The centering and leveling error ecl needs more

Analysis of the Antennaâ&#x20AC;&#x2122;s Setup Errors at the Global Navigation Satellite System Measurements

1286

caution as it affects both the geocentric and the ellipsoid coordinates. This error has a mean value of about

e cl 2

, which is significant for many applications.

[2]

The real magnitude and the azimuth of the ecl is very difficult and almost impossible to be known. Therefore, careful laboratorial checks of the tribrach

[3]

should be carried out before each campaign. Otherwise, special manufactured pillars or bases for precise centering should be used in order to eliminate

[4]

this error at the level of Âą0.1 mm. The above analysis is significant for monitoring networks or infrastructure stake-outs, as the uncertainty of the calculated coordinates by the GNSS may be largely augmented.

[5]

[6]

References [1]

M.S. Rawat, V. Joshi, B.S. Rawat, K. Kumar, Landslide movement monitoring using GPS technology: A case

[7]

study of Bakthang landslide, Gangtok, East Sikkim, India Journal of Development and Agricultural Economics 3 (5) (2011) 194-200. J.F. Zumberge, M.B. Heflin, D.C. Jefferson, M.M. Watkins, F.H. Webb, Precise point positioning for the efficient and robust analysis of GPS data from large networks, Journal of Geophysical Research: Solid Earth 102 (2012) 5005-5017. S. Shimada, Y. Bock, Crustal deformation measurements in central Japan determined by a global positioning system fixed-point network, Journal of Geophysical Research: Solid Earth 97 (1992) 437-455. G. Bomford, Geodesy, 4th ed., Clarendon Press, Oxford, 1980. Leica Geosystems Solutions Centers Website, http://www.leica-geosystemssolutionscenters.com/Site/In strument%20PDF's/GPS%20Systems/Viva/VivaGNSS_E quipList.pdf (accessed Jan. 1, 2013). D.E. Wells, W. Beck, D. Delikaraoglou, A. Kleusberg, E.J. Krakiwsky, G. Laschappele, et al., Guide to GPS Positioning, University of New Brunswick, Fredericton, New Brunswick, Canada, 1986. A. Fotiou, C. Pikridas, GPS and Geodetic Applications, Ziti Publications, Thessaloniki, Greece, 2006.

Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1287-1294 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

DAVID

PUBLISHING

Evaluating Land Surface Changes of Makassar City Using DInSAR and Landsat Thematic Mapper Images Ilham Alimuddin1, 2, Luhur Bayuaji2, Rohaya Langkoke1, Josaphat Tetuko Sri Sumantyo2 and Hiroaki Kuze2 1. Department of Geology, University of Hasanuddin, Makassar 90221, Indonesia 2. Center for Environmental Remote Sensing, Chiba University, Chiba-Shi 863-8522, Japan Abstract: Urban growth has been a major issue in environmental monitoring and changes occurred on land surfaces have been monitored by applying remote sensing as well as ground measurement. Most major cities in the world have experienced land subsidence phenomena on some parts of them due to the load of development and modernization. Excessive extraction of groundwater for the needs of industry has led to the condition where the water table drops, and this can possibly trigger subsidence, as observed in Indonesian cities. In this study the authors have shown that the application of DInSAR (differential interferometric synthetic aperture

radar) technique using Japanese Earth Resources Satellite-1 Synthetic Aperture Radar JERS-1 SAR data can reveal subsidence conditions in the studied Makassar city area. Landsat TM (thematic mapper) images were used to evaluate the change of land cover during the observation period of 1994-1999. Makassar is flat, covered mainly by alluvium deposit that is vulnerable to the load of constructions, and volcanic formations which is porous and will easily be degraded by groundwater extraction. It is found that mostly the subsidence has occurred in the western part of the city, including the industrial district, reclamation area, trading center area and the seaport area. The ground survey has indicated that high human activity exists in every point of subsidence. It is likely that various human activities such as ground water pumping and construction work should have affected the local subsidence phenomena in Makassar, as in the case of other large-scale cities in Indonesia. Key words: DInSAR, JERS-1, surface changes, urban growth, Landsat TM.

1. Introductionď&#x20AC; The impact of modernisation often appears as urbanization. It is natural that where a centre of civilization exists, the flow of development will gather therein. It is needed to study how one city grows by accommodating the impact of civilization and to examine if the growth is safely sustainable for the people occupying the area. As the number of population increases, more and more agricultural, shrub, and even swamp land areas are changed into industrial and construction areas, especially in rural areas surrounding the former city boundary. In addition to the increase in the usage of groundwater, such land cover changes can result in shortage of Corresponding author: Ilham Alimuddin, master of geographic information systems, research fields: concept and application of remote sensing and geographic information systems for geomorphological and geological changes. E-mail: ialimuddin@hotmail.com.

water supply in the hydrologic cycle. In urban areas, one of the particular concerns is the occurrence of land subsidence that will in turn cause flood. Makassar, the capital city of the South Sulawesi Province, in relation to this issue has been a target of urbanization since the old era. Remote sensing methodologies on the other hand are useful for the study of land subsidence, as seen in their applications to some of the big cities worldwide [1-3]. One of the most recent studies is the one over China by Perissin and Wang in 2011 [4] using the advanced technique of PS InSAR (persistent scatterer InSAR). The recent advancement of remote sensing technology has made it possible to map detailed terrain conditions ranging from local, regional to global scale with specific use and accuracy. The SAR (synthetic aperture radar) sensor onboard JERS-1 satellite provides the ability to map the earth surface

Evaluating Land Surface Changes of Makassar City Using DInSAR and Landsat Thematic Mapper Images

1288

topography and deformations independently of weather conditions despite any cloud cover or solar illumination. SAR records simultaneously the intensity and phase of the signal reflected from the surface. The phase is related to the travel time of the radar pulse between the spacecraft and the ground. The interferometric combination can be used to derive DEMs (digital elevation models) for an area [5]. Various methods have been employed, with the latest methods using the DInSAR [6] and Permanent Scatterer Insar [7]. Cities in Indonesia have been investigated using this technique was Jakarta [8, 9], Semarang [10, 11] and Bandung [12, 13]. The present paper evaluates the application of DInSAR technique by measuring the dimension of land subsidence phenomena that has occurred in the city of Makassar, which has been one of the notable centers of south eastern Asian civilisation as an urban hub since 16th century. The DInSAR investigation of the Makassar city has not been sought before, to the best of people’s knowledge.

Makassar city covers an area of 175.77 km2 divided into 14 sub districts. The city lies on the geographic coordinate of 119°18'27,97"-119°32'31,03" East Longitude and 5°00'30,18" -5°14'6,49" South Latitude. The landform is relatively flat, classified as alluvial plain with topography levels from 0-21 m above sea level (Fig. 1a). Geologically, the city is covered by four types of formation, Camba Volcanic Formation, Salo Kalumpang Volcanic formation (which mainly consists of fine sediment clastic of volcanic eruptive rocks but mostly eroded), a small area of Limestone Tonasa Formation and alluvium formation deposit as recent weathered material. In general, the authors can find three types of rock units, basalt, tuff and breccia derived from volcanic origins and sediment deposit like fine to coarse sand (Fig. 1b). The population of the city was 0.94 million in 1990, which increased to 1.2 million in 2010 [14], causing the increased use of both land surface and ground water. The rapid urbanization has made Makassar as a centre for economic development in eastern part of Indonesia. On the basis of the statistics of Makassar

(a) Study area Indonesia

(b) Geology map

Fig. 1

Study area: (a) Makassar city boundary ; (b) The geological map of the area.

Evaluating Land Surface Changes of Makassar City Using DInSAR and Landsat Thematic Mapper Images

City, population has been increasing due to the development and urbanization. Hence, the situation continues while people long for development to have better lives. The population increase triggers industries to develop new areas for business and construction. When the governmental control is limited in the rural area surrounding the city, the agricultural, shrub and even swamp spaces are developed, which in the future could generate land subsidence due to the extraction of water through wells. This mechanism has been suspected as the major cause of the subsidence of the urban land phenomena.

2. Data and Methodology This research utilized eight scenes of JERS-1 SAR images of level 0 covers a swath area of 75 km2 in descending modes with 35.5 degree of incident angle with acquisition date ranging from 1993 until 1998, but the area focused for the subsidence study is only 175.77 km2. DInSAR analysis was performed using SIGMASAR software developed by JAXA [15] combined with ENVI and ArcGIS software for implementing the GIS analysis. The DInSAR processing uses two pass interferometry to create an interferogram from two pairs of intensity (single-look, complex, SLC (single look complex) images. Subsequently, the differential interferogram is flattened and unwrapped to obtain the deformation map of the subsidence area, while evaluating the depth of subsidence from the interferogram. The flow chart of the DInSAR process can be seen in Fig. 2 [16, 17]. Based on the visual observation of Landsat images, urban development can also be seen from historical changes of the land cover. Landsat image acquired in September 1999 was used to create landuse map of Makassar in 1999 and Landsat image acquired in 1994 to create landuse map 1994. The load of development can be seen from the conversion of rice paddies, dry field and homogenous forest into business, services,

1289

and industry area. This conversion can obviously be observed in the northern part of the city. The city expansion also can be seen from the settlement and landuse change that bring more urban concentration to the area. The subsidence analysis is also supported with Landsat TM acquired in 1994 and Landsat ETM acquired on September 20, 1999. These Landsat images have been chosen in line with the acquisition dates of the SAR images. These images can be seen in Fig. 3. Field campaigns were conducted in September 2009 and January 2011 with handheld GPS (global positioning system) instruments. All supporting data are georeferenced to WGS (World Geodetic System) 1984 GIS (Geographic Information System) platform. This can be observed on the northern part and the southwest near the coastal line. The new high rise apartments, hotels and public facilities were constructed on this part of the city. Industrial area where warehouses and factories were built along the highway burdens the less compacted soil of coastal land. DEM

Simulated SAR

Slave

Master

SAR processing

DEM Co-registration Image co-registration Fringe removal Interferogram generation Differential interferogram

Phase unwrapping

Geocoding

Deformation map

Fig. 2

Phase unwrapping

Geocoding

DTM DTM

Schematic flow chart of DInSAR processing.

1290

Evaluating Land Surface Changes of Makassar City Using DInSAR and Landsat Thematic Mapper Images

(a)

(c)

(b)

(d)

Fig. 3 Intensity image: (a) Landsat TM_FCC_432 acquired on Aug. 29, 1994; (b) Landsat ETM_FCC_432 acquired on Sep. 20, 1999; (c) Intensity Image of JERS-1 data acquired on 19941011; (d) JERS-1 intensity image acquired on Aug. 19, 1998.

3. Results and Discussion As mentioned earlier, the authors processed eight datasets of JERS-1 SAR to create seven pairs to DInSAR images. Due to satellite orbital errors and influence of atmospheric conditions during the acquisition and considering the baseline difference of the two image used as master and slave images, three of the pairs have shown incoherence hence cannot be further analysed. In Fig. 4, the authors can observe colour coding patterns on the four images in some areas that show some consistencies while other areas display bands of interferometry noises. The authors have chosen the pair image of 1995/1996 to be analysed in detail, as shown in Fig. 5, the coherence image in Fig. 5a, a subset image in Fig. 5a and the deformation image in Fig. 5a.

The subset of the image that shown the indication of slight subsidence at the western part of the City of Makassar was then overlaid with high resolution image to confirm the subsidence location supported by the pictures taken from the ground survey in Fig. 5. The colour coding estimates a slight subsidence of 5-15 cm per year in particular area especially with the load of heavy settlement. The authors have shown that the application of DInSAR technique using JERS-1 data can reveal subsidence conditions in the study area. Mostly the subsidence occurred in the northern part of Makassar city during the time interval studied here, though the population density in northern part is lowest among the entire city regions. Industrial district, reclamation area, trading centre area, international airport and the

Evaluating Land Surface Changes of Makassar City Using DInSAR and Landsat Thematic Mapper Images

Antenna direction

(b)

(a)

1291

Satellite direction

-5.9 cm

5.9 cm

(c)

(d) Fig. 4 DInSAR processing images on the LOS (line of sight ), all datasets are on descending mode: (a) pair of 1995/1996; (b) Pair of 1996/1997; (c) pair of 1997/1997; (d) pair of 1997/1998, later image is master and earlier image is slave.

(a)

(b)

deep

shallow

(c) Fig. 5 DInSAR processing images of Makassar City: (a) coherence image of 1995/1996; (b) DInSAR Image pair of 1995/1996 images; (c) the deformation image after the unwrapping process.

seaport are built in this region. The centre of the subsidence with the subsidence-affected coverage area can also be estimated easily. It has been found that the subsidence occurred in separated regions with different land usage. Nevertheless, the ground survey has indicated that high human activity exists in every point of subsidence. Various human activities such as ground water pumping and construction working should have affected the local subsidence phenomena in Makassar,

as in the case of other large-scale cities. The main cause of subsidence in Makassar has not been revealed because of the complex feature of the phenomena. However, the result of the present study strongly suggests that the human activity and land use alteration are influencing the geomorphological changes in this city. Field campaign conducted in September 2009 revealed some locations that indicate the incidence of land subsidence and the fact that some parts of the city are having load of building

1292

Evaluating Land Surface Changes of Makassar City Using DInSAR and Landsat Thematic Mapper Images

P1 P3 P2

Fig. 6 2007.

Focus on deformation image of Tamalate area and surrounding overlaid with Quickbird image acquired on May 6,

Fig. 7 Pictures taken from the field observation indicating the occurrences of land subsidence, picture code correspond with the location in Fig. 6, red arrow indicates subsidence.

construction that make the city experience of slight movement of its earth surface. New building construction of warehouses can be seen in picture P1 taken in the area of Tallo, New

housing and modern apartment as well as community business complex in P2. Evidence of subsidence can be seen in Paotere, in Panakkukang, in Mariso and in Tamalate. On one of the main road, the soil load can

Evaluating Land Surface Changes of Makassar City Using DInSAR and Landsat Thematic Mapper Images

be a thickness of 15-20 cm (Figs. 6 and 7).

4. Conclusions and Future Study DInSAR method is used to estimate subsidence phenomena which has been derived and applied in this study. Continuous information of subsidence area will be useful for urban maintenance and urban development field, as one important factor for planning and construction works. So far, only few subsidence-related studies have been carried out using SAR data over urban area. The authors have tried to apply JERS-1 SAR although not all pairs can give good coherence due to the baseline and atmospheric aspects. The authors have successfully implemented the DInSAR processing technique in measuring the dimension of the land subsidence. The incidences in some areas show evidence of from 5-15 cm of subsidence shown by field observation conforming the result of DInSAR processing images. Although the main cause of subsidence in Makassar has not been revealed because of the complex feature of the phenomena, the result of the present study strongly suggests that the human activity and land use alteration are influencing the geomorphological changes in this city. In the future, as the City of Makassar will be growing larger and denser, it needs monitoring that even slight changes on its surface can be detected as it is prone to seasonal disaster such as floods and subsidence. With this DInSAR method, the authors hope to utilize newer SAR datasets to retrieve the rate of subsidence happened.

[3]

[4]

[5]

[6]

[7]

[8]

[9]

[10]

[11]

[12]

References [1]

[2]

D. Raucoules, C. Colesanti, C. Carnec, Use of SAR interferometry for detecting and assessing ground subsidence, Comptes Rendus Geosciences 339 (2007) 289-302. R.S. Chatterjee, B. Fruneau, J.P. Rudant, P.S. Roy, P.L. Frison, R.C. Lakhera, et al., Subsidence of Kolkata (Calcutta) City, India during the 1990s as observed from space by differential synthetic aperture radar

[13]

[14]

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interferometry (D-InSAR) technique, Remote Sensing of Environment 102 (2006) 176-185. N. Phien-wej, P.H. Giao, P. Nutalaya, Land subsidence in Bangkok, Thailand, Engineering Geology 82 (2006) 187-201. D. Perissin, T. Wang, Time-series InSAR applications over urban areas in China, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 4 (1) (2011) 92-100. H.A. Zebker, J. Villasenor, Decorrelation in interferometric radar echoes, IEEE Transactions on Geoscience and Remote Sensing 30 (1992) 950-959. L. Bayuaji, R.F. Putri, J.T. Sri Sumantyo, Combination of L,C and x-Band SAR data for continuous monitoring of land deformation in urban area by using DInSAR Technique, in: Proceeding of International Conference on Space, Aeronautical and Navigational Electronics, Incheon, 2012. A.H. Ng, L. Gea, X. Li, H.Z. Abidin, H. Andreas, K. Zhang, Mapping land subsidence in Jakarta, Indonesia using PSI (persistent scatterer interferometry) technique with ALOS PALSAR, International J. of Applied Earth Observation and Geoinformation 18 (2012) 232-242. L. Bayuaji, J.T. Sri Sumantyo, H. Kuze, ALOS PALSAR D-InSAR for land subsidence mapping in Jakarta, Indonesia, Canadian J. Remote Sensing 36 (1) (2010) 1-8. H.Z. Abidin, H. Andreas, I. Gumilar, M. Gamal, Y. Fukuda, Y.E. Pohan, et al., Land subsidence of Jakarta (Indonesia) and its relation with urban development, Nat Hazards 59 (2011) 1753-1771. M. Marfai, L. King, Monitoring land subsidence in Semarang, Indonesia, Environmental Geology 53 (2007) 651-659. A.M. Lubis, M. Sato, N. Tomiyama, N. Isezaki, T. Yamankuchi, Ground subsidence in Semarang-Indonesia investigated by ALOS PALSAR satellite SAR interferometry, Journal of Asian Earth Sciences 40 (2011) 1079-1088. J.T. Sri Sumantyo, M. Shimada, P.P. Mathieu, H.Z. Abidin, Long-term consecutive DInSAR for volume change estimation of land deformation, IEEE Transactions on Geoscience and Remote Sensing 50 (1) (2012) 259-270. H.Z. Abidin, H. Andreas, I. Gumilar, D. Murdohardono, Y. Fukuda, On causes and impacts of land subsidence in Bandung Basin, Indonesia, Environ Earth Sci. 68 (2013) 1545-1553. Makassar Statistics Bureau, BPS (Badan Pusat Statistik), Kotamadya Makassar, Makassar in Figures, Annual Report of 1993-1998, and 1999. (in Indonesian and English)

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[15] M. Shimada, , Verification processor for SAR calibration and interferometry, Adv. Space Res. 23 (8) (1999) 1477-1486. [16] P.A. Rosen, S. Hensley, I.R. Joughin, F.K. Li, S.N. Madsen, E. Rodriguez, et al., Synthetic aperture radar

interferometry, Proceedings of the IEEE 88 (3) (2000) 333-382. [17] H. Fan, K. Deng, C. Ju, C. Zhu, J. Xue, Land subsidence monitoring by D-InSAR technique, Mining Science and Technology 21 (2011) 869-872.

Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1295-1300 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

D DAVID

PUBLISHING

The Industrial Heritage and the New Architecture: Teaching, Researching, Designing the Place Identity Monica Bruzzone and Roberta Borghi Department of Civil Engineering and Architecture (DICATEA), University of Parma, Genoa 16142, Italy Abstract: The new architecture may provide unusual opportunities for the abandoned areas involved by former industrial processes, both in the city centers and in the landscape. In fact, it may create new centralities and give new collective function for deprived areas. The case study of the architectural and educational project for a new museum park devoted to the technique and the science in the Apennine’ s landscape near Parma (Italy) may give an interesting point of view about the role of the teaching and the research of the architecture in the former industrial heritage, and to avoid the abandonment and the pauperization of the territory around. Key words: Identity, industrial heritage, architecture, architecture design studio, teaching, research.

1. Introduction The architecture may provide new opportunities for the places development, particularly in those urban or rural landscapes where the end of a productive tradition have established heavy losses, both from a social point of view, with the gradual loss of a local identity—well represented by that specific technique or industry—and from a environmental point of view, with the creation of large urban voids and the presence of a disused industrial heritage, often rich in quality. In this case study, the new architecture may represent a important way of giving opportunities to a deprived area by introducing new functions or new central points and by giving, as well, a new social identity for the place. The industrial heritage and the large areas deprived by the abandonment of factories, workshops, mines or pits after the end of the production, may represent at the same time the remains of an ancient technical identity and the opportunity for designing a new identity, giving the territories who hosted the industry a new cultural or productive life, starting from both the physical and immaterial rests of a lost past. Corresponding author: Monica Bruzzone, Ph.D., research fields: architecture, architectural, design, industrial heritage and places identity. E-mail: monica.bruzzone@unipr.it.

The new architectural design has to consider, therefore, a wide number of variables to produce an effective new architectural project. First of all, it is necessary to make a deep research about the characteristics of the places and the needs of its community, so to interpret the true values of the old industrial vocation and to understand what memories you have to save and how can you represent them by the new architecture. Then it is necessary to ask which functions can you assign to the site, in order to turn a negative polarity in a new public centrality, where it can be pleasant to live, to work, to study, to attend cultural events or just to “stand and stare”. A wrong design process may deliver the place, once again to oblivion and neglect. At the same time, it is important to consider how the research, the teaching and design, may be complementary for rethinking the former industrial heritage and for rediscovering the local identities. The Research Group AMR/APR [1], working with the Department of Civil Engineering and Architecture (DICATeA), University of Parma, is experiencing since many years how the rural areas and the small towns of the Emilian Appenines may be requalified by a new kind of architecture. As well the main objective of this study is to demonstrate how to contribute to the

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development of a former industrial area by the new functional, social and architectural project, and how a new centrality for the community or, if you want, a new “piazza” may give new values for a wider area, creating new kinds of use for that place.

the countryside and the new architecture. The former industrial sites on the Emilian Appenines may be interesting examples of how represent a new heritage to discover, by the creation of new centralities to the development of wider areas.

2. The Industrial Heritage and the Role of the Architecture

2.1 The New Architecture: Tool for the Development of the Former Industrial Sites

It is important to note that the main references of these studies can be found in some Italian researches of the 1970s and 1980s and in the definition—or better in the re-definition—of some specific cultural values based on the delicate balance between the work of men and the landscape development [2]. The interpretation of the so called “Italian condition” by the researcher Emilio Sereni, Lucio Gambi and Giulio Bollati [3], aims for instance, at defining new interests for the rural areas as actors of the architectural process as well as the metropolitan areas. A concept already developed in Italy by Giuseppe Pagano [4] just before the Second World War. The connections between the men’s work and the physical characteristics of the territory are also deepened in 1970s by the Italian geographer Lucio Gambi. He clarifies that the relationship between the place and the human’s work is an essential goal in the development of any community. The man settles in areas with good characteristics for the life and the production, and then he modifies those places and makes them appropriate for the lifestyle of the community and the techniques of settlement. As opposed to the Paul Virilio theory of “crepuscular dawn” [5] as a condition of de-territorialisation and loss of cultural reference points, the “sense of place” defined by Gambi [6] may represent an effective tool for the design process in the landscape. As well, the most recent definition of “family relationship between men and land” by Salvatore Settis [7] may be a good starting point for a new way of understanding the relationships between

The Research Group “Architecture Museums Networks”, is working since many years on the subject of redeveloping little centres and parts of landscape through the insertion (or better you could say the “infill”) of a new architectural polarity inside the landscape. The new project may be a public place or a collective building or just a square, but it may have the special skill of interpreting the social needs of the community and creating a new centrality for this specific “horizon of territory” or “unity” of landscape itself. So you aim at building a new identity by the construction of new characters for that specific society starting from the ancient memory of the site. The project is deepened by the collaboration with some important institution for the local heritage such as the IBC (Istituto per i Beni Artistici, Culturali e Naturali), that is the institute for Cultural Heritage of the Region Emilia Romagna, in Italy. Some of this studies became architectural projects or bachelor’s thesis by the members of the research group. 2.2 The Officine Reggiane, Reggio Emilia Italy The ancient Officine Meccaniche Reggiane is a former industrial site where, since the first years of the 20th century there was a wide production of railways components and artillery projectiles. The industry became famous in the late 1930s for the production of the fighter aircrafts. After the end of the production, in the early 1950s, the wide site of the Reggiane became a urban void. The research group aimed firstly with the degree thesis by Roberta Borghi (Fig. 1), at redesigning the whole site of the Reggiane, building a new centrality with services, cultural activities, work

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Fig. 1 A model of the Officine Meccaniche Reggiane, design by architect Roberta Borghi, year 2008.

Fig. 2 Sketch of the science center and glass museum Bormioli, design by architect Luca Vacchelli (2010-2012).

spaces and public spaces for the city of Reggio Emilia. The starting point of the design process was the interpretation of a peculiar ancient axis and streets, designing a museum dedicated to the Officine Meccaniche Reggiane, a way of transmitting the memories of a still strong identity.

long and narrow halls, is very adequate for the needing of a contemporary science centre, with interactive boxes and large-scale reconstructions. As well the older building is dedicated to the Glass Museum Bormioli: a place for the memory of the lost identity of the factory.

2.3 The Glass Museum and Science Centre Bormioli in Parma

3. The Petroleum Museum Park in Fornovo di Taro, Parma

The “Bormioli Rocco & Figlio” is one of the oldest glassware in the city of Parma. Around the first workshop, built in 1854, it was created a new neighbourhood inhabited, in the beginning, by the workers families. Now the neighbourhood is a part of the city of Parma, extended further beyond the old perimeter of the nineteenth century. After the end of the production, the ancient factory became a wide urban void in the middle of a residential district of Parma and today it aims at becoming a new centrality for Parma as a polycentric city. The recent proposal by the architect Luca Vacchelli, aim at creating a new cultural polarity to give the area a functional characterization, a kind of specialization. The study for this area is commissioned by the owners: The “Bormioli Rocco” and it will be evaluated by the municipality of Parma. The Science Centre (Fig. 2) is a missing cultural polarity for Parma, and at the same time the environments of the old factory, with galleries and

The project of a Petroleum Museum Park (Fig. 3) for the little town of Fornovo di Taro, nearby Parma is an important case study where teaching, researching and designing are considered three important parts of a common process. This study is now starting an operating phase after receiving funding by the MIUR, the Italian Ministry of University and Research, based on the annual programs proposed by the Italian Law 6/2000. In this part of the architectural design process, the research group aims at giving new life and new characters to a former industrial site, with a multimedia exhibit and a design of guidance in the park, so the architecture may be the most important

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opportunity for the redevelopment of a wider part of landscape in a pleasant part of the Apennines. The research program is based on an agreement between the University of Parma, the Municipality of Fornovo and the Oil Company Gas Plus Italiana SpA, owner of the areas. The aim of the research is to recover the industrial and the natural heritage in one of the oldest oilfields in Italy (1860-1970), for both tourist and educational purposes. The mine, developing a local self extractive system called “metodo Fornovo”, was intensively exploited in the early 20th, and almost exhausted during the autarkic period of the Fascism, when it was one of the focal points for the supply of crude oil for the army. The mine is also the place where it was established the Società Petrolifera Italiana, now called Ente Nazionale Idrocarburi, one of the most important operators of hydrocarbons in Italy. Some oil wells and natural gas wells have remained active up to 1970, until the production became uneconomic. Since that time, after the reclaiming of the wells and some industrial plants, the ruins of the workshops, the forge, the power station, the pumping stations in the wood and the miners village, have lost their former function and now they remain as well as rests: objects trouvé immersed in the clay hills of Fornovo. The dissemination of the extraction techniques and the memory of the ancient oilfield, may play an important role in the educational program of the Province of Parma, where there are not museums or study centers devoted to disseminate the sciences and the techniques. As a verification process of an evolving theoretical subject, the Architecture Design Studio (Second year of the Degree in Architecture) is working on the architectural and urban design of these depressed areas by the introduction of a new architecture as a new public centrality able to give a new identity and new social functions to the place. The work is divided in two different phases. In the first semester a preliminary approach to the project, is

devoted to transmit some cultural issues and some positions of the architectural debate. In the second semester, each student have to apply these notion to a design process connected with the place of the Oilfields of Fornovo di Taro. In the first part, students have to learn by basis elements of the architectural process as well as the construction and the assembly, the cut or the excavation of solid corps, making exercise of creating a new architectural space by the addition or the subtraction of matter. This is a way to investigate how the architectural design should begins from theoretical premises and the personal poetry, but it may become architecture only through the “contamination” with the materials and the techniques. The first exercise is the design of a small exhibition pavilion with a dimension of 6 m × 6 m × 6 m, for the exhibition of an only artwork, as suggested in the literary essay: “The museum in the third millennium” by Eco [8]. The creation of a 1:20 scale maquette of the small building becomes necessary to learn the three-dimensional role of the architectural projects (Fig. 4). The second exercise is the redrawing of two different existing buildings: an exhibition pavilion and a most complex building chosen between lists of architectural models of 20th century (Fig. 5). The second semester is focused on the project of a Petroleum Museum Park in the valley of Fornovo,

Fig. 4

The architectural models of the first semester.

The Industrial Heritage and the New Architecture: Teaching, Researching, Designing the Place Identity

Fig. 5 The oil pavilion: A new exhibitions pavilion for the area of Vallezza.

seat of the ancient oilfield. Students are called to reflect on different scales of the design: from the landscape to the building, up to the exhibition design. Students are divided in groups of two or three people. Each group is called to design a park museum with the aim of enhancing the place by deepening some specific architectural and functional themes, such as a meeting place for tourists and for the bikers,

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pathways and roots trough the industrial rests, but also a study place for disseminating the identity of the former oilfield (Fig. 6). After deepening the park, each group may design the new cultural centrality with a museum devoted to the technique and the scientific culture, a study centre with a small auditorium, a library and a laboratory for the children’s activity, but also a place for guests, such as a little diffused hotel (in the little town of Vallezza, the former miner’s village), or a guesthouse for tourists and schools visiting the place. In the last month of the year each group deep an only building in scale 1:100. This approach to the design process aim at giving the students the special skill of “seismographs” of the needs of the place having a direct approach with inhabitants and better understanding the place’s problems. In parallel with this teaching process, also useful to raise public awareness of, and with funds obtained

Fig. 6 A sample of the architectural design studio works. The museum park of Fornovo. A masterplan and the design of the cultural center in the Cantiere Respi, the heart of the former industrial site, by the student Valentina Manente (Architectural Design Studio 2-2013).

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The Industrial Heritage and the New Architecture: Teaching, Researching, Designing the Place Identity

from the Ministry, it is processing the project of a small pavilion or a multimedia installation by bringing in schools and public institutions in order to dissemitate the scientific culture connected with the oil and the memory of a lost cultural identity, and to trigger a virtuous cycle of rigeneration of this area, as well as of Fornovo di Taro, by increasing the value of an important industrial activity forgotten today and by giving a new centrality to a nice part of the Appenines very interesting but very little used today.

discipline of architectural composition is also composed by the poetry. This third subject may be suggested or alluded or commented on by a teacher, who wants to communicate students the importance of this topic through the architectural debate and through every design process, but it is a matter quite delicate and fragile. As well can not certainly teach it, because it may became a part of each student’s cultural baggage.

The new centrality should be able to generate a new

The authors would like to thank the MIUR (Italian Ministry of Research), the Municipality of Fornovo di Taro (Parma) and the Gas Plus Oil Company, for the financial support to the research. Also we would like to thank the AMR Research Group and the department Dicatea—University of Parma.

complexity and liveability of the place, hosting different activities, planning diversified and easily accessible areas, and becoming, therefore, a strategic element for a wider part of the landscape.

4. Conclusions Teaching about the design process and the architectural composition to young students in their

Acknowledgments

References [1]

first years of university can be a good opportunity to experiment a kind of teaching method based on three areas of teaching. The first area is the theory. The main theoretical issues and the ideas of the architectural debate may be discussed with the students in order to communicate them the complexity of the architectural problems trough the centuries, and to stimulate the critical thinking. The second area is the technique. Only through the contamination between the architectural ideas and the materials, forms and techniques you can appreciate the discipline of architecture as a concrete fact and something three-dimensionally accomplished. But in addition to the theory and the technique, the

[2]

[3] [4] [5] [6] [7] [8]

Reconnecting the Design Research with Actual Demands of the Territory, AMR (Architecture Museums Network) and APR (Architecture Landscape Network), University of Parma, 2005. M. Bruzzone, L. Serpagli, Le radici anonime dell’abitare moderno, Ph.D. Thesis, University of Trento, Franco Angeli, Milano, 2012. R. Romano, C. Vivanti, I caratteri originali, Encyclopeda, Torino, 1972. G. Pagano, G. Daniel, Architettura Rurale Italiana, Quaderni della Triennale, Hoepli, Milano, 1936. P. Virilio, Crepuscular Dawn, Semiotext(e), NY, USA, 2002. L. Gambi, I valori storici dei quadri ambientali, in: Storia d’Italia, Einaudi, Torino, 1972. S. Settis, Paesaggio, Costituzione, Cemento, La battaglia per l’ambiente contro il degrado civile, Torino, 2010. U. Eco, Il museo del terzo millennio, Bilbao, June 25, 2001.

Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1301-1322 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

DAVID

PUBLISHING

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica Walter Salazar1, Lyndon Brown2 and Garth Mannette1 1. Seismic Research Centre, The University of the West Indies (UWI), St. Augustine, Trinidad and Tobago 2. Earthquake Unit, The University of the West Indies (UWI), Mona, Kingston, Jamaica Abstract: The authors performed single mobile microtremor measurements at 218 sites at KMA (Kingston Metropolitan Area) with the objective of estimating the amplification effects due to the earthquake ground motion on the surface geology. The Fourier transform was applied to the most stationary parts of the triaxial wave motion recordings for each individual site and applied the traditional Nakamura technique, namely, the horizontal to vertical spectral ratio (H/V) to retrieve the predominant shear wave period of vibration of the soil profiles above the bedrock. The results yield predominant long periods of about 3.0-4.0 s in the port area and the waterfront, 1.0-2.0 s in the central part of Kingston, 0.3-1.0 s in Portmore and very stiff soil conditions in the surrounding area of the city. The results coincide fairly well with previous geological studies in the region, geotechnical data in boreholes, gravimetric measurements and strong motion recordings, suggesting a high degree of amplification of ground motion in the whole period range of engineering interest. Additionally, the authors obtained the liquefaction vulnerability factor Kg proposed by Nakamura based on the H/V ratio of microtremors. The results suggest that the port area, the waterfront and the Port Royal are highly susceptible to liquefaction. Finally, the authors obtained fundamental periods of vibration based on microtremor measurements on the roof and the basement of four important buildings in the KMA and indicated future lines of research employing ambient noise measurements on structures. Key words: Microtremors, Rayleigh and S-waves, amplification factor, fundamental period of vibration.

1. Introductionď&#x20AC; Several researches documenting the destructiveness of several seismic events have established the pervasive influence of the sedimentary deposits on the preferential distribution of damages, such distribution appears to correlate well with the degree of amplifications caused by the surface geology, the authors can then regard the local distribution of the ground shaking intensity as a phenomenon closely related to the filtering effects of the soil profile [1, 2]. Several studies have shown that Nakamuraâ&#x20AC;&#x2122;s technique [3] for estimating shear wave resonant periods is a robust method that can yield useful information regarding the soil profile of a site in the near surface. In this work, the authors study the site effects in KMA Corresponding author: Walter Salazar, doctor of engineering, research fellow, research fields: earthquake engineering and engineering seismology. E-mail: walter.salazar@uwiseismic.com.

(Kingston Metropolitan Area) by performing single mobile microtremor measurements at 218 sites. In the first section, the authors introduce the surface geological setting of KMA based on available references for the city, secondly, an explanation of the methodology involved in the collection and processing of the microtremor data is presented and then outlined the theoretical background of the Nakamura technique to retrieve the quasi-transfer function of the soil profile. From this study, a new isoperiod contour map and a 3-D basin depth for the KMA have been proposed. The quasi transfer functions obtained by the microtremors are validated with available gravity, boreholes and strong motion data for the KMA. Finally, the authors assessed the liquefaction potential based on their microtremors recording, the water table level and the ground level shaking proposed by the new seismic hazard maps for Jamaica presented in the previous issues.

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Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

2. Geological Setting Metropolitan Area

Kingston

The Liguanea Plain is a quaternary alluvial fan of the Hope River that drains the mountains to the northeast of Kingston forming the southern boundaries of the KMA. It consists of poorly sorted sands and gravels interspersed with layers of clay and sand. Occasionally, boulders of volcanic rock and conglomerate are also found [4]. The fan rises gently from sea level at Kingston harbour to more than 200 m elevation at Mona in the northeast, where it meets the Hope River at the base of the mountain range, the northern limits of the KMA used in this study. Few wells dug in the fan sediments have reached bedrock, hence the shape of the underlying basement and the thickness of the alluvium are not well known. To better constrain depth to basement rock, a gravity survey was conducted along two transects across the Liguanea Plain [5]. The results indicate a gradual deepening to 500-600 m at the Kingston waterfront with a more uniform depths of 300-400 m with undulations found along an east-west profile. The average shear-wave velocity of the fan sediments was estimated from well logs to be 320-495 m/s and the basement rock was assumed to be Miocene Limestone. The surrounding hills to the northwest in Stony Hill and on the Limestone plateaus of Long Mountain all sit on Tertiary Limestone, these are areas of recent uplift and show high levels of fault escarpments, to the northeast are the highly jointed clastic sedimentary and volcanoclastic rocks of the Wagwater Formation showing recent slope failure deposits where currently new developments are continuously being built on the colluvial slope deposits of former landslippage.

city that was destroyed in the major earthquake M 7 [6] of 1692 is made up of discontinuous coral reefs connected by sands and gravels deposited by longshore drift from the estuaries of the Hope, Cane, Yallahs and Morant Rivers to the east of Kingston. The predominant deposits are loose sand deposits which are highly susceptible to liquefaction due to its shallow water table and poorly compacted deposits. The northwest limit of the KMA in the area of Stony Hill sits at an elevation of 1,400 ft. with the underlying rocks of the White Limestone plateau of the eastern extension of the Troy Formation. Most of the waterfront sections of the city are built on engineered fill on which sits significant sections of the infrastructure of the city. There are also some sections of artificial fill or man-made ground which are non-engineered, which forms parts of downtown Kingston, Kingston harbour, the industrial zone leading to the airport, and also in the west area of the Newport where the activity is again modified by engineered fill, as shown in Fig. 1. Most of the rocks in the surrounding mountain overlooking the plain are extensively faulted. The southern part of the Wagwater Trough and westernmost extension of the Plantain Garden fault system separates the Liguanea Plain from these outcrops. The northwest trending Wagwater Fault at the northern limits of the Liguanea Plain is associated with many micro-earthquakes [7]. On average over 200 earthquakes are recorded annually by the Jamaica Seismograph Network. These events have epicenters both locally (on-land and within the coastal waters) and regionally (outside of the local region but within 400 km from the Jamaica

The southern extension of the tombola that drains

Seismograph Network). At least 10 of these

alluvial deposits along the Palisadoes now exists as one

earthquakes are described as felt events. Current

continuous landmass previously existing as individual

earthquake frequency data from the earthquake unit at

cays that have progressively been joined with some

UWI (University of the West Indies) Mona show the

amount of anthropogenic interference. The westward

highest levels of seismicity is associated with the

extension of the Palisadoes is located at the old

eastern part of Jamaica (Kingston St. Andrew, Portland

buccaneering city of Port Royal. This once infamous

& St. Thomas) accounting for over 75% of the earthquake

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

Chalk

Non-limestone

Recrystallized

Rubbly

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Yellow limestone

Fig. 1 General geological map of Kingston Metropolitan Area and microtremor points surveyed (black solid circles). The polygon includes the wave motion of microtrermors and the horizontal to vertical H/V spectral ratios presented in Figs. 5 and 6. The crosses (X) denote boreholes indicating the depth of the bedrock or the maximum depth reached (>). The red triangles denote strong motion stations (SMS1 and SMS2).

events on the island. The new probabilistic seismic hazard maps developed for Jamaica at rock site conditions presented in previous issues confirm that KMA is subjected to a moderate/high seismicity based on a peak ground acceleration of 0.24 g for 475 years return period and spectral accelerations for periods of 0.2 s and 1.0 s yielding levels of 1.05 g and 0.16 g respectively for 2,475 years return period.

3. Theoretical Background of H/V Ratios of Microtremors Microtremors are a general term for constantly existing minute vibrations at the surface of the ground

with body and surface waves being the main component of microtremors. Microtremors show specific characteristics of the surface geology, and are periodic and contain the amplification characteristics of the soil, which is often referred to as site-effect. The periodic characteristics of microtremors are similar to the ones during earthquakes, however, the amplitude of microtremors is quite small caused by human activity, machinery, traffic, etc.. Due to the close relation between the nature of microtremors and the fundamental dynamic behavior of the surface soil layers, these small vibrations are useful and also well known in the field of earthquake engineering. To assess

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Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

the transfer functions, the authors used the traditional method of Nakamura, the horizontal to vertical spectral (H/V) ratio. While studying the characteristics of microtremors, Nogoshi and Igarashi [8] found a conspicuous similitude of the horizontal to vertical spectral ratios (H/V) of microtremors to that of Rayleigh waves. This led them in the first instance to suggest Rayleigh waves as the main component of microtremor recordings. This constitutes the origin of the horizontal to vertical spectral ratio technique applied in the estimation of the amplification of the horizontal motion in the presence of surface layers using microtremors [9, 10]. Nakamura [3] revisited this method and brought it back to the engineering community as non-reference site technique providing a theoretical interpretation in the form of his semi-quasi transfer spectrum model incorporating the effects of Rayleigh and S-waves in his formulation. Nakamura’s formulation of the H/V spectral ratio departs from the assumption that the vertical component of motion reaches the surface without undergoing significant amplification within the frequency range of interest in engineering, thereby retaining the characteristics of the horizontal motion at the engineering bedrock. Nakamura [3] proved the validity of this crucial assumption at the Tabata and Kanonomiya sites in Japan for the usual frequency range of practical interest in engineering, namely, from 0.125 Hertz to 10 Hertz (0.1 s to 8.0 s). The authors define Hi(f) and Hb(f) as the surface and engineering bedrock horizontal Fourier amplitude spectrum of microtremors, respectively. If f denotes the frequency of ground motion, then the authors can express the site effects function Gi(f) at a site i, by applying the following expression:

Gi ( f )  Hi ( f ) Hb ( f )

(1)

It seems worth noting that although dealing with microtremor recordings, Eq. (1) results in a transfer function formulation quite similar to that proposed by Borchedt [11] for earthquake ground motion recordings. In their original formulation, Nakamura [3]

assumed that the energy of microtremors comprises both body and surface waves, and that the surface sources generate Rayleigh waves equally affecting the horizontal and vertical components of motion [9]. If the authors assume that the vertical motion due only to body waves undergoes no amplification, then the authors can express the effect of the Rayleigh waves on the vertical motion ES (f) as follows:

Es ( f )  Vi ( f ) Vb ( f )

(2)

According to this development, ES yields 1.0 in the absence of Rayleigh waves, whereas values over 1.0 indicate the effect of Rayleigh waves. The next step in this formulation comprises the vertical and horizontal components of motion assuming a similar effect of Rayleigh waves on both. On these premises, the formulation of the horizontal to vertical motion spectral ratio (H/V) aims at eliminating the Rayleigh wave’s effect via calculation of the ratio Gi(f)/Es(f): H V 

Hi(f)/ Hb(f) Gi ( f ) H i ( f ) V b ( f ) (3)   * ES ( f ) Vi ( f ) / Vb ( f ) Vi ( f ) H b ( f )

According to the previous assumptions, at the engineering bedrock, the ratio Hb(f)/Vb(f) equates 1.0 within a relatively wide period range. Accordingly, the authors can estimate the soil transfer function by taking the Hi(f)/Vi(f) ratios of the surface recordings.

4. Microtremors Processing

Survey

and

Data

The authors performed microtremors survey at Kingston Metropolitan Area (Fig. 1) in November 2011, June 2012 and November 2012. A total of 218 measurements with an average of 500 m-1 km spacing was made employing a triaxial Tokyo Sokushin 24 bit sensor, model CV-374A with a flat response between 0.1 Hz to 10 Hz (Fig. 2) and a recording system of 100 samples per second, the sensors measured micromotion in terms of acceleration. The following six steps were adopted to perform the surveys and to analyse the data (Fig. 3): (1) The authors tried to make the measurement whenever in a silent environment for at least 5 min

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

1305

Fig. 2 Transfer function for the Tokyo Sokushin Sensor CV374-A (Courtesy of Isamu Yokoi).

Fig. 3 Flowchart showing the methodology for data collection and digital signal processing.

at each location (trying to maintain the survey, interval, however there are some locations where the authors had to collect in the closest possible location relative to this interval), since the instrument can easily record surrounding noise such as heavy traffic. These are

reflected in spikes on the records that can perturb the periodic features of the microtremors. The horizontal sensors were located with north-south and east-west orientations (magnetic north); (2) Samples of 20 s of the stationary parts of the

1306

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

recording were selected initially for processing; (3) For each sample, the authors applied a baseline correction that targets the elimination of the noise associated with the unknown zero-level line associated with long period components, this serves to remove the signal offset responsible for constant shifts of all acceleration values. The Fourier transform was then applied to the records and with the band pass raised cosine filter. The authors selected the low and high cutoff frequencies in the filter according to the dynamic amplification factor (flat response) provided by the sensor manufacturer (Fig. 2); (4) The authors applied the inverse Fourier transform to obtain the corrected acceleration time history for each record; (5) For each selected stationary part, the authors

computed the resultant Fourier acceleration amplitude spectrum and the correspondent uncertainties for the horizontal and vertical components of motion. The authors smoothed the spectra applying a Parzen Window with a bandwidth of 0.4 Hz; (6) Finally, the authors calculated the horizontal to vertical spectral ratio (H/V) employing the resultant vector of the orthogonal north-south and east-west components of motion and averaging the results for all the stationary parts selected for each record, the maximum and minimum ratios were computed as well. The authors identified the peak in the H/V ratio and located it in the geographical information system. They plotted the spectra for 0.1 s to 8.0 s coinciding with the period range of interest for earthquake engineering practice.

Fig. 4 Horizontal to vertical spectral ratio (H/V) for different lengths of sampling data: microtremor measurement recorded at 2011/11/20 13:38:50 with coordinates 17째59.301' N, 76째47.855' W (Top); microtremor measurement recorded at 2011/11/28 11:28:34 with coordinates 17째59.6082' N, 76째46.5924' W (Bottom). The maximum, minimum and the mean of the H/V ratios are presented for each recording.

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Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

It should be noted that an iterative procedure is sometimes necessary to improve the resolution and to reduce the uncertainties in the results especially when long period ground motion is predominant in the spectrum (Fig. 4). Stationary samples of 20 s sometimes are not enough for the resolution of the spectrum above periods of 1.0 s: in this case, the authors increased the duration of the samples to 60 s and repeated the procedure for (ii) to (vi) in Fig. 3. In other cases, the authors repeated the measurements recording for 15 min in those locations where long period ground motions appeared and increased the time of the samples and also employing 60 s to make the signal processing scheme. 4.1 Analysis and Interpretation

VR 

4H VS

(4)

Inverting Eq. (4) for H yields an average depth of ≈ 200 m in the Liguanea Plain above the Miocene Limestone (see depth of the boreholes in Fig. 1), which

 

(5)

where, μ is the rigidity modulus and ρ is the density. Taking typical values for the limestone of μ = 24 GPa, ρ = 2.7 g/cm3 yields a VR = 943 m/s. Employing an optional Eq. (6) to find the depth of the bedrock H employing microtremors is as follows [13]: H 

The authors present in Fig. 5 the horizontal wave motion of microtremors for the transverse section from north to south depicted in Fig. 1. It is clear that the characteristic of microtremors varies considerably along KMA in terms of amplitude and period of motion. Generally, the amplitude and the period increase from the mountain region in the north toward the south at the shore in the port area, the amplitude varies from 0.1 cm/s2 to 2.0 cm/s2 and the period from 0.1 s to 3-4 s. The authors present the plots of the H/V ratios for the same points in Fig. 6 and plot the predominant periods for the whole city in Fig. 7. From east-west, there is a minor change in the periods of the unit. Along the Liguanea Basin and at the eastern part of the waterfront, the authors observe an average period T of 2.0 s confirming the presence of the thick alluvial deposits on KMA basin (Fig. 7). The average shear wave velocity (VS) of the fan sediments is estimated from well logs to be 320-495 m/s (410 m/s) [5]. Taking the fundamental period T in seconds of a soil profile equal to: T (s) 

is considered here as the engineering bedrock. The microtremor results primarily coincide with the general geology setting of the basin where poorly consolidated alluvial deposits with the deepest boreholes down to depth at least 200 m, Aspinall and Shepherd [12] suggest layers of sand retained in the shallower parts with clays comprising deposits of the deeper parts. The shear wave velocity VR for the limestone is equal to:

VR 4 AS F g

(6)

where, AS is the ratio VR/VS and Fg is the predominant frequency based on microtremors. Setting VR = 943 m/s for the limestone and taking AS = 943/410 = 2.30 and Fg as 0.50 Hz (T2 = 2.0 s) yields a depth H = 205 m. Note that Eq. (6) is equivalent to Eq. (4), however, the computed AS ratio determines the contrast between the rock and the soil that is related to the sharp peak and the through observed in the H/V ratios (Fig. 6c). The longest periods of about 3.0 s to 4.0 s are observed in the port area to the west of KMA and the sand spit that connects Portmore and KMA, presumably reclaimed land areas with the water table is commonly close to the surface. The results coincide with a soil profile depth of about 310-410 m as a result of natural sedimentation and landfill. Also, Aspinall and Shepherd [12] suggest that the deepest part may exceed 300 m in this area. The general trend of the increasing depth of the sediments from north to south in KMA is also confirmed by the gravimetric survey performed by the National Disaster Research [5] yielding thickness of the alluvial deposits ranging from 100 m to 600 m. The authors found along the Palisadoes spit different periods of vibrations of the soil profiles, at the western part in Port Royal area the periods yield 1.0-2.0 s

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

1308

0.2

(1) 2011/11/22 17:22:13

0 -0.2

0.2

(2) 2011/11/22 16:57:02

0 -0.2

(3) 2011/11/21 15:49:34

0.4 0 -0.4

0.4

(4) 2011/11/21 15:23:35

0 0.8

-0.4

(5) 2011/11/19 18:32:34

0 -0.8

0.8

(6) 2011/11/19 18:06:42

0 0.8

-0.8

(7) 2012/11/27 16:20:32

Acceleration (cm/s2)

0 -0.8

(8) 2012/11/27 15:52:47

0 -2

(9) 2011/11/19 13:56:54

0.8 0 -0.8

(10) 2011/11/20 16:13:10

0.8 0

(11) 2011/11/25 14:17:51

-0.8

0 -2

(12) 2012/11/29 17:42:58

2 0

(13) 2011/11/20 17:10:16

0.8 0 -0.8

(14) 2012/11/29 17:15:36

-2

2 0

0.4

(15) 2011/11/24 18:35:41

-2

0 -0.4

(16) 2012/11/28 18:41:47

0.8 0

0.4

(17) 2012/06/23 18:04:57

-0.8

0 -0.4

(18) 2011/11/24 18:04:12

0.4 0 -0.4

Time (s)

Fig. 5 Wave motion microtremors for the N-S component inside the polygon shown in Fig. 1.

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

suggesting a loose intermediate soil depth profile of about 100-200 m. The shortest periods in the range of 0.3-0.6 s were found at the Norman Manley International Airport possibly due to compaction works related to the construction of the airport, however, soft soil conditions were found at the western edge of the runway with a period of 1.5 s, suggesting a different degree of soil compaction during the construction process of the airport. At the eastern edge of the spit in

1,000

1309

the Harbour View, the authors found again period of 1.5 s related with the sediments deposited by the Hope River. The spectral shape of the H/V ratios and the absolute acceleration Fourier spectra introduce an insight of the wave propagation of microtremors (Fig. 8): the sediments above bedrock behave as a high-pass filter allowing the Rayleigh waves to propagate in the surface layers, however, the Rayleigh waves can not

(a)

100

(b) (c) Fig. 6 Horizontal to vertical spectral ratio (H/V) for the points inside the polygon depicted in Fig. 1, the numbers next to the ratios correspond to the same numbers depicted in Fig. 5, the authors computed the geometrical mean for the horizontal component of motion, T1 is nearly 1/2T2 indicating a high contrast between the sediments and the basement rock in KMA.

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Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

propagate in the period range of the predominant period of the surface layers T2 but can transmit the energy peak around the period of minimum group velocity (½ of T2 corresponding to the trough period T1 in Figs. 8b-8d) which constitutes an Airy Phase. Note that through period T1 is nearly half of the peak period T2 in the H/V spectral ratios presented in Figs. 6 and 8. As a conclusion, the effect of multiple reflections of the S-waves is composed mainly around the predominant period T2 and the period of maximum energy transmission of the Rayleigh waves is about a half T2 ≈ T1 [14]. The sharp peak (T2) and a sharp trough (T1) suggests a high velocity contrast between the basement rock (VR)

Chalks

Non-limestone

and the velocity of the surface layers (VS) yielding VR/VS ≥ 2.5 [10]. It is noted that the VR/VS ratio yields 2.3 between the limestone and the alluvium. Anomalous H/V ratios above 100 are observed at some sites (Fig. 7), the authors explain this phenomenon in Section 5. A further examination of the H/V ratio for the harbour area (port) is presented in Fig. 9. The H/V ratio reflects three peaks at 3.0 s, 1.0 s and 0.4 s, which presumably constitutes the fundamental mode and the harmonics of the soil profile in the port. An important characteristic of this quasi transfer function is that the peak observed in the second period of vibration is clearly caused by the trough in the vertical component physically representing the change from retrograde

Recrystallized

Rubbly

Yellow limestone

Fig. 7 Predominant period of soil based on horizontal to vertical spectral ratio (H/V) for the 218 points in Kingston Metropolitan Area.

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

1311

(a)

(b)

(c)

(d)

Fig. 8 Rock site (a) and sediments sites (b-d) characterized by the effect of multiple reflections of the S-waves around the predominant period. Left: Fourier amplitude spectra for the horizontal and vertical components of microtremors. Right: H/V ratios, the horizontal motion is taken as the geometric mean of the N-S and E-W components. 10

1000 1,000

H/V ratio

Amplitude (cm/s2 * s)

100 100

Graph 1 N-S E-W Vertical

10 10 0.1

0.2

0.5

1 Period (s)

3 2

1 0.5 0.3 0.2

2011/11/29 17:42:58

0.1 0.1

0.2

0.5

1 Period (s)

(a) (b) Fig. 9 A further examination of the H/V ratio for the harbour area (port): (a): Fourier amplitude spectra for the horizontal and vertical components of microtremors; (b) H/V ratios, the horizontal motion is taken as the geometric mean of the N-S and E-W components. The site is located in the harbor area with H/V ratios showing the fundamental mode and the harmonics.

1312

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica 10 100 H/V Ratio

Amplitude (cm/s2 *s)

(a)

10 Graph 1 N-S E-W Vertical

(a)

0.1

100

2011/11/23 16:41:28

H/V Ratio

Amplitude (cm/s2 *s)

(b)

10 (b) 1

10 100 H/V Ratio

Amplitude (cm/s2 *s)

2011/11/23 12:55:02

0.1

(c)

10 (c)

Maximum

Mean Minimum 2011/11/23 18:55:18

0.1

(d) 100

H/V Ratio

Amplitude (cm/s2 *s)

(d)

2012/06/24 18:56:14 0.1

1 0.1

0.2

0.5

1 Period (s)

0.1

0.2

0.5

1 Period (s)

Fig. 10 Fourier amplitude spectra for the horizontal and vertical components of microtremors at Portmore area (Left); H/V ratios, the horizontal motion is taken as the geometric mean of the N-S and E-W components (Right).

to prograde particle motion at the surface, in other words, the ellipticity of the fundamental modes of Rayleigh waves explain such peak at the second mode of vibration, but is clearly not related with the resonant S-wave fundamental period in the soil profile. This feature is also observed within the municipality of Portmore (Figs. 10a-10c) with the peaks in the period range of 0.3 s to 1.0 s caused by the trough in the vertical component, however, the shapes of the absolute spectra and the H/V ratios yield different

features for the wave propagation in comparison with the Liguanea Plain, the harbour area and Port Royal. It is noticed that the Portmore area was part of the flood-plain of the slow-moving Rio Cobre with the result of a deposition of great thickness of fine grained materials and with intercalations of sand deposits [15]. As a consequence of such intercalation of materials, the authors can suggest that the peak observed might correspond to the second mode of vibration constituting the predominant period in this case [16].

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

A flat H/V ratio of 1.0 is observed at the foot of the limestone Port Henderson Hills near the Green Bay (Fig. 10d) and ratio of 1.0 is observed in the shore of the city for all frequencies of motion. A period of 1.0 s is observed in the shore of the city. Stiff soils or rock site conditions are generally found on the hills surrounding KMA in the limestone hilly areas, yielding an H/V ratio ≈ 1.0 for periods between 0.1 s and 2.0 s (Fig. 8a), however, the authors observed soil sediments at some places in Stony Hill at the northern of KMA yielding fundamental periods of 1.2 s. The authors also found visible outcrop-rock conditions toward to the north of KMA at the district of Roehampton and surrounding areas (i.e., Constant Springs and Arlene Gardens); these geological conditions were confirmed with the microtremor recordings. At the north and east of Mona Reservoir, the authors found the most irregular pattern for the period of vibration between 0.6 s and 1.0 s, there is no clear indication of a regular soil structure in this area, an intercalation of coarse gravels and sands are reported for this region [5]. The authors developed an isoperiod map for KMA employing the 218 microtremors points (Fig. 7) and interpolating the period values to a grid of 15 m × 15 m via application of the minimum curvature method (Fig. 11). This map shows similar patterns for the work of Wald and Allen [17], yielding average shear wave velocities in the first 30 m based on topographic slopes at KMA. In a similar way, the authors developed a 3-D model sediment depth for KMA derived by inverting the depth H of Eq. (4) setting an average shear wave velocity of 410 m/s and using the predominant periods obtained by each H/V ratio of microtremors (Fig. 12). The thickness distribution in the city appears to correlate well with the MM (modified Mercalli) intensity distribution observed for the earthquake of January 13, 1993, M 5.5 and with shallow depth of 15 km located in the Blue Mountains [6]. Despite the epicenter was located to the north-east at

1313

a distance of about 15 km from central Kingston, high intensities of VIII MM were reported in the waterfront where the thickest sediments are located according to our model. Another earthquakes located 200 km away from KMA in the Oriente Fault Zone at the South Cuba has triggered intensities of IV MM in the Liguanea Plain. 4.2 Comparison of Earthquake Motion Data and Microtremors The authors tried to elucidate the level of amplification in the KMA employing earthquake data and comparing them with microtremors, employing the H/V ratio and an amplification factor developed by dividing the actual ground motion by the motion estimated at rock conditions using the ω2 model. Brune [18] proposed a simple model to explain the earthquake source in the frequency domain. He considered a simple circular fault of radius r that ruptures over its whole area at the same time [19]. The method relates the spectrum of the shear radiation to the stress released across the fault surface. The high frequency level of the source spectrum is controlled by the stress parameter (stress drop) and the low frequency level proportional to the seismic moment, then the observed spectra in this model depend on the moment magnitude and the stress drop [20]. The salient characteristics of the displacement spectrum in the low frequency level are given by Haskell [21]: o 

Mo 4 Rv s 3

R

(7)

where, Mo is the seismic moment in dyne-cm, R is the radiation pattern coefficient (0.55 for average radiation pattern of the double-couple radiation),  is the density, vS is the crust shear wave velocity (km/s) and R is the hypocentral distance. At higher frequencies longer than the corner frequency fc in the spectrum amplitudes falls as f2 or ω2, where, ω (omega) denotes the circular frequency (ω = 2πf). The corner frequency can be found by:

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

1314

  f c  4 . 9  10 6 v S   Mo

  

1/3

(8)

where,  is the stress drop in bars. Then displacement spectrum at a distance R is: D( f ) 

Mo 4 Rv s 3

  1  R *  2  1   f / f c  

(9)

McGuire and Hanks [22] suggested incorporating the quality factor QS(f), to account the free-surface effect (using a factor of F = 2) and the vectorial partitioning of energy into two components of equal amplitude (factor of V = 0.71). Also, they suggested that the Fourier amplitude spectrum of acceleration can be obtained by multiplying the displacement spectrum by (2πf)2. Then, in a compact form, the Brune ω2 model acceleration spectrum near the source for horizontal component is Ref. [23]:  1 Ac( f )  (2 f )2 CM o 2  1   f / fc  

C 

R V

(11)

4 v s 3

The stress drop and the seismic moment are used to define the source spectrum, which is obtained in Eq. (10) using the expression inside the brackets multiplied by (2f)2 or prescribing R = 1.0. The authors should remember that this constitutes an “apparent source spectra” since it refers to the fact that these representations are what the authors deduce from far-field observations [24]. To obtain the seismic moment Mo (dyne-cm), we use the moment magnitude MW and using the formula [25] as follows: MW 

2 log M o  10 . 7 3

(12)

The authors calculated the amplification factors from the earthquake strong motion recordings

 e fR / QS ( f )vS  *F  R 

dividing the observed Fourier amplitude spectra by (10)

where, 660000 660,000

the corresponding theoretical spectra employing Eq. (10) setting 100 bars of stress drop, the QS(f) from

Stony Hill

3.8

2.5

1.5

650,000 650000

ng Lo

Latitude (m)

655,000 655000

n ai nt ou M

Hunts Bay

0.6

645,000 645000

0.2

Port Henderson Hills

Caribbean Sea

0 760,000 760000

765,000 765000

770,000 770000

775,000 775000

Longitude (m)

Fig. 11 Isoperiod map for Kingston Metropolitan Area, the units for the period are in s.

780,000 780000

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

1315

Stony Hill

-20 -40 -60 -80 -100 -120 -140 -160

780,000

-180 -200 -220

660,000

775,000

-240 -260 -280

655,000 770,000

-300 -320 -340

650,000

-360

765,000

645,000

-380

760,000

Fig. 12 A 3-D sediments depth model for Kingston Metropolitan Area based on the period of the soil deposits and an average shear wave velocity of 410 m/s, the units of depth are in m.

McNamara et al. [26], vS = 3.8 km/s at the correspondent distance R from the earthquake and compare with both, the H/V ratio derived from microtremors and the strong motion records; although originally proposed to analyze microtremor data, Lermo and Chávez-García [27] applied the H/V ratio technique to earthquake ground motions recorded on soft sediments in Mexico City, and obtained a good coincidence with microtremor-based predominant periods. Figs. 13 and 14 illustrate the amplification spectra resulting from the application of this procedure for an earthquake event on 2011/05/06 09:29:22 UTC and Mw 4.7 with an epicenter north-east of Kingston (18.087 N, 76.652 W) and a shallow depth of 5 km. For the station at the Toll Office in Portmore (SMS1), it is clear that a very good match is observed for the predominant peak for H/V of microtremors at 2.0 s and the amplification factors derived from the ω2 model. Similar characteristics are observed for the strong

motion at the station SMS2 on Portmore Bridge for the same earthquake at the period of 2.5 s, the sharp peak at 0.65 s derived from the ω2 model and the H/V could be attributed to the structural response being the instrument located on one of the pillar footings of the bridge. The authors performed the microtermor measurement about 25 m away from this station due to the immediate inaccessibility, being the footing of the bridge surrounded by water. For both stations, the H/V obtained by the earthquake recording present peaks in longer periods, but not so well defined as the ones obtained by microtermor recordings and the ω2 model. The authors attribute these differences to the fact that the vertical component comprised of body waves undergoes no amplification for microtremors as stated by Nakamura [3], while significant amplification can take place in the vertical component during earthquakes with earthquake epicenters located near the station. Konno and Ohmachi [10] suggested a simple formula

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

1316

Amplification

Mean H/V of Microtremors Max. and Min. H/V of Microtremors Derived from Omega square model H/V of earthquake data 0.1 0.1

Period (s)

Fig. 13 Comparison of transfer functions of microtremors and strong motion data for the Toll Office at Portmore (SMS1 in Fig. 1). 10

Amplification

0.1 Mean H/V of Microtremors Max. and Min. H/V of Microtremors Derived from Omega square model H/V of earthquake data

0.01 0.1

Period (s)

Fig. 14 Comparison of transfer functions of microtremors and strong motion data for the Bridge at Portmore (SMS2 in Fig. 1).

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

1317

1000000 1,000,000 Harbour Area 100000 100,000

10,000 10000 Liquefaction Index (Kg)

Liguanea Plain (Central West)

1,000 1000 Harbour Area

Port Royal

100 100

HIGH LIQUEFACTION POTENTIAL

10 10 Mountain region 11

LOW LIQUEFACTION POTENTIAL

0.1 0.1 -4

0 4 Distance from Coast Line (km)

(a)

Amplitude (cm/s2 * s)

1000 1,000

300

Maximum

200

H/V ratio

100 100 10 10

100

Mean

50 30

Graph 1 N-S E-W Vertical

0.1 0.1 0.1

0.2

0.5

1 Period (s)

Minimum

10 0.1

0.2

0.5

1 Period (s)

(b) Fig. 15 The harbour area, Port Royal and some areas at the Liguanea Plain have a high liquefaction potential: (a) Liquefaction index Kg based on microtremor measurements depicted in Figs. 5 and 6 and the polygon depicted in Fig. 1; (b) absolute Fourier spectrum and anomalous H/V spectral ratio in the harbor area.

for the amplification factor AS using H/V ratio of microtremors, as follows: ‫ܣ‬ௌ ൎ ܴெ஻

(13)

where, RMB denotes the ratio at the peak. In this case, we can attribute an amplification factor of 4 at 2.0 s for SMS1, of 3.0 at 2.5 s for SMS2.

5. Preliminary Assessment of Liquefaction Potential Nakamura [13] proposed a simple technique to investigate the liquefaction potential based on microtremor measurements, namely the vulnerability index Kg for the surface ground, as follows:

1318

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

‫ܭ‬௚ ൌ

஺೒ మ ி೒

(14)

where, Ag is the amplification factor referenced to the engineering bedrock and Fg is the predominant frequency of the soil profile (the inverse of the fundamental period), both values can be taken from the horizontal to vertical spectral ratio (H/V) of microtremors, Ag is considered to be the H/V ratio at the predominant frequency [10]. Values of Kg greater than 20 are considered likely to liquefy. The authors applied this method to the cross section in Fig. 1 and H/V ratios presented in Fig. 6. The results show that the harbour area, Port Royal and some areas at the Liguanea Plain have a high liquefaction potential (Fig. 15). It is worth mentioning that anomalous H/V ratios above 100 for long period components between 2-2.5 s are observed in the Liguanea and the harbor area (Fig. 6, H/V ratios number 8, 7 and 11) due to the very low amplitude and flat vertical absolute Fourier spectra at these sites indicating a small contribution of Rayleigh waves in the micromotion, however, the authors observed the same fundamental periods in the H/V ratio at other sites where significant vertical amplitudes appear. Despite the difference in the energy in vertical component of motion at different sites, this phenomenon confirms that the quasi-transfer function provides the fundamental period due to the multiple refraction of SH waves in the surface ground layers regardless of the influence of the degree of Rayleigh waves. These characteristics were observed also at some points in the waterfront area. As a further evidence, Nakamura [14] suggested that in the case of a low effect of Rayleigh waves, it is possible to estimate both the fundamental periods and the second mode caused by the multiply reflections of S-waves. These characteristics were observed also at some points in the waterfront area. Performing continuous measurements at these sites during one or two weeks will help to clarify the distinction of long period microtremors or microseisms due to ocean waves excitation and short period microtermos (Kanai’s microtremors) due to human

activity, traffic, machinery, etc. [28]. The new Probabilistic Seismic Hazard Assessment for Jamaica (see the article in the previous issues) suggests a Peak Ground Acceleration for 475 and 2,475 years return period KMA of 0.25 g and 0.45 g respectively at rock site conditions in KMA; the saturated sediments on those areas can be classified as sand/silty where the water table is located at the surface. Liquefaction phenomena were observed during the earthquake of 1907 at Port Royal (Fig. 16).

6. Microtremor Measurments on Buildings We measured microtremors in the roof and in the basement of four reinforced concrete buildings in KMA in order to investigate the translational period of vibration. The buildings for which we measured the microtremors were: Ministry of Agriculture, Petroleum Corporation of Jamaica, Ministry of Health and UDC (urban development

corporation)

Office

Centre

Building. In order to eliminate the influence of the soil on the roof measurements on the buildings, we divided them by the micromotion recorded on the basement. Fig. 17 depicts the amplification functions of the buildings showing clear predominant periods of vibration in the transversal and longitudinal directions (Table 1). As a

Fig. 16 Liquefaction phenomena is still evident in the “Giddy House”, an ammunition store at Port Royal during the 1907 earthquake.

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

1319

MINISTRY OF AGRICULTURE 40

Graph 1 Transversal Direction Longitudinal Direction

Amplification

0 0.1

0.2 0.3

0.5

1 Period (s)

PETROLEUM CORPORATION 80 Graph 1 Transversal Direction Longitudinal Direction

Amplification

0 0.1

0.2 0.3

0.5

1 Period (s)

MINISTRY OF HEALTH 25 Graph 1 Transversal Direction Longitudinal Direction

Amplification

0 0.1

0.2 0.3

0.5

1 Period (s)

UDC OFFICE CENTRE BUILDING Graph 1 Transversal Direction Longitudinal Direction

Amplification

0 0.1

0.2 0.3

0.5

1 Period (s)

Fig. 17 Transfer function for reinforced concrete buildings based on microtremor measurements at the top and the bottom of the buildings.

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Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

Table 1 Fundamental period of vibration and damping as percentage of the critical for buildings in Kingston Metropolitan Area for transversal and longitudinal directions. Name of the building Ministry of Agriculture Petroleum Corporation of Jamaica Ministry of Health UDC Office Centre Building

Fundamental period (s) Transversal Longitudinal 0.22 0.27 0.48

0.58

0.76 0.73

0.90 0.79

preliminary observation, we note that the amplification factors between the transversal and the longitudinal directions differ twice and sometimes three times, the lowest ones being always in the transversal directions for which we observe the shortest fundamental period of vibration, in other words, the microtremor measurements reveal that the longitudinal direction of the buildings is more flexible than the transversal direction. An appropriate seismic coefficient might have been taken into account during the phase structural design in accordance with the architectural building configuration and the stiffness/flexibility observed in both directions.

7. Conclusions At the Kingston Metropolitan Area, intensities of MM VI or greater have been reported at a rate of 20 times per century, constituting the largest rate amongst all Jamaican cities [29]. The authors clearly attribute this fact to effects of the surface geology on the earthquake ground motion in the city yielding average depth of the sediments ranging from 200-300 m and periods of about 2.0-3.0 s in the Liguanea basin. Despite the fact that the predominant period of vibration based on the H/V of microtremor measurements coincide well with available geological information, a more precise “level of amplification” during future earthquakes at KMA is still a question to solve. The authors have elucidated amplification factors of about 3-4 for periods ranging 1.0-2.0 s employing a very limited amount of earthquake ground

motion and microtremor data, but such few samples lead to inconclusive statements for the whole city, even more for short period components of ground motion (0.1-1.0 s). In this regard, fundamental future work in the area to perform microtremors array observation is recommended in order to retrieve the shear wave velocity profile information reaching the bedrock based on conventional methods as the SPAC (spectral auto correlation). Such arrays might be done in different parts of the city in order to give proper amplification factors that are dependent of frequency, and to scale up the elastic design spectra developed in the seismic hazard assessment for rock site conditions presented in another article of the previous issues. The first microzonation maps for KMA must be done for both, the level of amplification with its correspondent seismic loads and the liquefaction potential, which the authors have demonstrated, represents a high hazard especially in the Kingston harbour areas and Port Royal. Kingston ranks as the 7th largest natural harbour in the world and has a large concentration of infrastructure through the KMA like oil refineries, power generation plants and high rise buildings. The seismic hazard paper presented in this previous issues clearly demonstrated that a moderate size earthquake can produce long term economic impact in the country due to the substantial level of shaking, and the amplification phenomena caused by the presence of unconsolidated and saturated soils in the region. The source of the microtremors can be elucidated if continuous measurements are performed simultaneously on rock and soil [28, 30] and compare their amplitude with those of ocean wave heights or changes in atmospheric pressure at the harbour. Their survey indicates that long period microseisms are present at rock site conditions observing a peak in the long period components (above 4.0 s) in the “absolute” Fourier spectrum that clearly does not correspond to the presence of sediments at these sites (i.e., Figs. 8a and 10d). Then the long period microtremors (microseisms) and short period microtremors (Kanai’s

Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

microtremors) must be distinguished in future research with continuous measurements at strategic points in the city at rock site and deep soil conditions. The deployment of a dense earthquake strong motion network in the KMA is a must in order to validate the results from the microtremors survey together with systematic boreholes data that can validate the microtremors array observation cited above and the amplification factors that would arise with the earthquake data. A future line of research in the region is the acquisition of the dynamic properties of medium and high rise buildings employing microtremors, namely the fundamental translational and rotational period of vibration and the damping ratio, especially in zones where the resonant phenomena is likely to occur.

Acknowledgments Maps have been prepared using ESRI Arc Map 10.1 (Arc View) Geographic Information System and SURFER Golden Software 8. This study has been funded by the World Bank as a part of the Risk Atlas Project for the Caribbean under the supervision of the DRRC (Disaster Risk Reduction Centre) at the University of the West Indies, Mona, Jamaica. The authors thank Paul Williams, Karleen Black, Raymond Stewart, Stephanie Grizzle, Laurel Choy (Earthquake Unit, Jamaica) and Omari Graham (SRC/UWI, Trinidad) for assisting the authors in the microtremors survey at Kingston Metropolitan Area. The authors also thank the following institutions that permitted them to make measurements at their facilities/buildings: (1) Kingston Container Terminal; (2) The Port Authority of Jamaica; (3) The Airport Authorities of Jamaica; (4) Jamaica Defense Force; (5) Urban Development Corporation; (6) Ministry of Health and the Environment; (7) Ministry of Agriculture;

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(8) Petroleum Corporation of Jamaica.

References [1]

W. Salazar, V. Sardina, J. Cortina, A hybrid inversion technique for the evaluation of source, path and site effects employing S-wave spectra for subduction and upper-crustal earthquakes in El Salvador, Bull. Seismol. Soc. Am. 97 (2007) 208-221. [2] W. Salazar, K. Seo, Earthquake disasters of January 13th and February 13th 2001, El Salvador, Seismological Research Letters 74 (4) (2003) 420-439. [3] Y. Nakamura, A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface, Quaterly Report of Railway Technical Research Institute 30 (1) (1989) 25-33. [4] R. Ahmad, E. Robinson, Geological evolution of the Liguanea Plain—The landslide connection, in: Proceedings of the First Conference, Faculty of Natural Sciences, The University of the West Indies, Mona, May 1994, pp. 22-23. [5] National Disaster Research, Inc., The Earthquake Unit, UWI, Mines and Geology Division, Jamaica, Kingston Metropolitan Area: Seismic Hazard Assessment Final report, U.S. Agency For International Development/Organization of American States, Caribbean Disaster Mitigation Project, Kingston Multi-Hazard Assessment, 1999, p. 82. [6] M. Wiggins-Grandinson, T. Kebeasy, E. Husebye, Enhanced earthquake risk of Kingston due to wave field excitation in the Liguanea Basin, Jamaica, Caribbean Journal of Earth Science 37 (2003) 21-32. [7] M.D. Wiggins-Grandison, Jamaican seismology and seismic hazard parameters, in: Jamaica Building Code Conference, Jamaica Pegasus Hotel, Kingston, Sep. 27-28, 2007. [8] M. Nogoshi, T. Igarashi, On the amplitude characteristics of Microtremors (Part I), Jour. Seis. Soc. Jap. 23 (1970) 281-303. [9] V. Rodríguez, S. Midorikawa, Applicability of the H/V spectral ratio of microtremors in assessing site effects on seismic motion, Earthquake Engineering and Structural Dynamics 31 (2002) 261-279. [10] K. Konno, T. Ohmachi, Ground-motion characteristics estimated from spectral ratio between horizontal and vertical components of microtremors, Bull. Seismol. Soc. Am. 88 (1998) 228-241. [11] R. Borchedt, Effects of local geology on ground motion in San Francisco Bay, Bull. Seismol. Soc. Am. 60 (1970) 29-61. [12] W. Aspinall, J. Shepherd, Modelling earthquake response of the Liguanea—St. Catherine Plain of Jamaica in: 8th

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Surface Soil Effects Studies Based on H/V Ratios of Microtremors at Kingston Metropolitan Area, Jamaica

Caribbean Geological Conference, Curacao, 1977. [13] Y. Nakamura, Seismic vulnerability indices for ground and structures using microtremors, in: World Conference on Railway Research, Florence, 1997. [14] Y. Nakamura, On the H/V spectrum, in: The 14th World Conference on Earthquake Engineering, Beijing, China, Oct. 12-17, 2008. [15] J. Turnosvsk, J. Shepherd, Microzoning for Earthquake Effects in Kingston, Report No. 2, Mines and Geology Division, Ministry of Mining and Natural Resources, Seismic Research Unit, The University of the West Indies, 1976. [16] W. Salazar, K. Seo, Spectral and amplification characteristics in San Salvador City (El Salvador) for upper-crustal and subduction earthquakes, in: 11th Japan Earthquake Engineering Symposium, Japan, 2002, pp. 329-334. [17] J. Wald, T. Allen, Topographic slope as a proxy for seismic site conditions and amplification, Bull. Seismol. Soc. Am. 97 (5) (2007) 1379-1395. [18] J. Brune, Tectonic stress and spectra of seismic shear waves from earthquakes, J. Geophys. Res. 75 (1970) 4997-5009. [19] L. Reiter, Earthquake hazard analysis, issues and insights, Surveys in Geophysics 13 (3) (1992) 297-298. [20] G. Atkinson, Earthquake source spectra in eastern north America, Bull. Seismol. Soc. Am. 83 (6) (1983) 1778-1798. [21] N.A. Haskell, Total energy and energy spectral density of elastic wave radiation from propagating faults, Bull. Seismol. Soc. Am. 54 (1964) 1811-1841. [22] R. McGuire, T. Hanks, RMS accelerations and spectral

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amplitudes of strong ground motion during the San Fernando, California Earthquake, Bull. Seismol. Soc. Am. 70 (5) (1980) 1907-1919. D. Boore, Stochastic simulation of high-frequency ground motions based on seismological models of the radiated spectra, Bull. Seismol. Soc. Am. 73 (6) (1983) 1865-1894. G. Atkinson, D. Boore, Evaluation of models for earthquake source spectra in eastern north America, Bull. Seismol. Soc. Am. 88 (4) (1998) 917-934. T. Hanks, H. Kanamori, A moment magnitude scale, J. Geophys. Res. 84 (1979) 2348-2350. D. McNamara, M. Meremonte, J.Z. Maharrey, S.L. Mildore, J.R. Altidore, D. Anglade, et al., Frequency-dependent seismic attenuation within the Hispaniola Island Region of the Caribbean Sea, Bull. Seismol. Soc. Am. 102 (2012) 773-782. J. Lermo, J. ChĂĄvez-GarcĂa, Are microtremors useful in site response evaluation?, Bull. Seismol. Soc. Am. 84 (1994) 1350-1364. K. Seo, On the applicability of microtremors to engineering purposes: Preliminary report of the joint ESG research on microtremors after the 1993 Kushiro-oki (Hokkaido, Japan) Earthquake, in: 10th European Conference on Earthquake Engineering, Rotterdam, 1995. J. Shepard, W. Aspinall, Seismicity and seismic intensities in Jamaica, West Indies: A problem in risk assessment, Earthquake Engineering and Structural Dynamics 8 (1980) 315-335. K. Seo, JICA Research and Development Program on Earthquake Disaster Prevention, The Japan Building Disaster Prevention Association, JICA (Japan International Cooperation Agency), 1997.

Oct. 2013, Volume 7, No. 10 (Serial No. 71), pp. 1323-1328 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA

DAVID

PUBLISHING

The Idea of “Architecture Stage”: A Non-material Architecture Theory Yuke Ardhiati1, 2 1. Department of Fine Art and Design, Trisakti University, Jakarta 11440, Indonesia 2. Department of Architecture, Tarumanagara University, Jakarta 11440, Indonesia Abstract: The purpose of this study is to find “the new theory” in the process of having quality “form” in architecture field which is usually visualized by the ruler through his ideology of his architectural work which is created by his architects. The study is about an urban design in architectural field related with space-power-knowledge. To reveal the meaning of the architecture objects is need to analyze the architectural object “form” as the culture-material, and to reveal the meaning of the objects through the hidden things related to the presence of the metaphysical data. To find “the new theory” used “grounded theory research”, the method is part of qualitative research which refers to Glaser and Strauss. The achievement study is finding the idea of “architecture stage” of the ruler, represented by Soekarno as the first Indonesian President. Through visual observation and spatial experiences in his several architectural works concerning the “Project’s Lighthouse” as his architectural work in Jakarta in the 1960s the idea of connectedness was found. He composes his architecture’s work by inserted the “architecture drama analogy” as metaphor for representing himself and his ideologist by exploring the Javanese Ancient’s as the basic design in the modern architecture at that time the east meet west. Key words: “Architecture stage”, grounded theory, khora, the ruler.

1. Introduction The ideologist is usually visualized by the ruler through his architectural work which is created by his architects. The same phenomena of the ideas of “architecture stage” abroad were revealed in the architectural legacies of Adolf Hitler in Germany, Joseph Stalin in the Soviet Union, Kubitchek in Brazil, Mao Tze Dong in the People’s Republic of China, and Nehru in India, also in Indonesia. However, there are different types in Indonesia. Soekarno’s architecture tacitly expressed his architectural knowledge in the manner of “eastern meets western”, resulting in a combination of differences between them. Soekarno has given “color” as sense of presence in the ideas of the “architecture stage Soekarnoestic” by combining the charm of the Indonesian culture by exploring Ancient Javanese form, Soekarno distinguished his Corresponding author: Yuke Ardhiati, Dr., research fields: architecture work, building conservation, theory and creative design for architecture and design. E-mail: yuke_ardhiati@yahoo.com.

architectural style based on Ancient Javanese culture as the basic design to modern architecture. This was done at a time when Hitler was composing his architectural style which is almost similar style when Stalin was composing the Stalinist Gothic. It also different when Kubitcheck was designing the capital city of Brazilia, when Nehru was composing Chandigarh by Corbusier, and when Shanghai, China was declared as the “Paris of the East” by local architects. The finding ideas of “architecture stage” in Indonesia was driven by desire, intervention and a sense of art of Soekarno’s concept by exploring the Javanese Ancient’s as the basic design in the modern architecture.

2. Method The paper is a part of architecture dissertation investigation to express the civilization created by the ruler represented by Soekarno, the first Indonesian President. The study based on the archival data is a part of la longue durée historical by Braudel, 1958 [1],

The Idea of “Architecture Stage”: A Non-material Architecture Theory

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it is architectural field related space-power-knowledge, to find “the new theory” used “grounded theory”. This method is also part of qualitative research referring to Glaser and Strauss. The achievement study is to find the idea of Soekarno as the ruler, when he creates the space, through visual observation and spatial experiences in his architectural works of the “Project’s Lighthouse” in Jakarta in the 1960s. The data are collected and named as coding, data analysis and memoing—the final step to develop a new theory [2]. The research objectives in architecture field are needed into three methods: (1) visual investigation; (2) phenomenology’s investigation; (3) to reveal the hidden meaning through the data metaphysical.

principle of life”. It is from the Old Javanese of Indonesian ancient as the basic idea to create the modern architecture. 3.1 The Jakarta City Planning

Hotel Indonesia; (5) the Istiqlal Mosque; (6) the

The Hotel Indonesia built as the pilot tourism and as the Indonesian’s Face during the Jakarta City Planning projects. Soekarno emphasized the culturization to dreams Jakarta City which is equivalent to the International city: Jakarta is as a beacon that leads directly to participate pushing development projects! The main idea of the Jakarta City Planning are composed the eight lines of Kebayoran Baru-Thamrin road inspired by the Brazilia City Plan. The Jembatan Semanggi or Semanggi Brigde is a clover bridge devided the four directions of the Jakarta. The corridors of Kebayoran—Thamrin looks like a “stage” resembled a big catwalk on architectural work. Fig. 1 shows the location of the “Project’s Lighthouse” in Jakarta in the 1960s in the main corridor of Jakarta.

National Monument; (7) the Wisma Nusantara; (8) the

3.2 The “Gedung Pola” Building

3. Results After investigated in the several Soekarno’s work in the “Project’s Lighthouse” in Jakarta in the 1960s, e.g., (1) The Jakarta City Planning; (2) the Gedung Pola; (3) the Main Stadium of Gelora Bung Karno; (4) the

Sarinah Department Store; (9) the Planetarium; (10) the Conefo’s Venue Building, a number of the city scale sclupture’s was found [3]: First,

Soekarno’s

works

were

inserting

his

ideologist as his architectural communication when he was creating the space of the “Lighthouse Project” in order to establishment his power. His works reflect the

idea

“architecture

stage”

toward

The Gedung Pola building is located in the heritage site of Rumah Proklamasi—the House of Proclamation on Jl. Pegangsaan Timur 56 Jakarta. In this place, Soekarno read the Declaration of Independence of Indonesia on August 17, 1945. Now, the heritage is already ruins of buried foundation and

the

architectural form which is similar to characteristic of khora [3]. Khora or Chora is a Greek term to express a “concept of space” designated by Plato in Timaeus [3-5]; Secondly, the “Lighthouse Project” looks like “the abstract space” referring to Lefebvre, its role to strengthen the social homogeneity through the architecture work with characterized: spectacularly, geometrically and phallic, was shown to the tenth of the architecture works to beautification of Jakarta Capitol City. The heritage buildings are contained with a monad which is the immortality “immaterial

Fig. 1 The location of the “Project’s Lighthouse” in Jakarta in the 1960s in the main corridor of Jakarta.

The Idea of “Architecture Stage”: A Non-material Architecture Theory

replaced by a big statue as the landmark of Soekarno’s position when his reading the text of proclamation. The open space building to facilitate the permanent exhibition for the development project of Semesta Berentjana Project years 1961-1969 is designed by Silaban. Fig. 2 shows the “Gedung Pola” building proposed by Silaban. 3.3 The Main Stadium Gelora Bung Karno Soekarno’s desire is as the host of the Asian Games IV on 1962 and must prepare the international venue standard with capacity around 110,000 people by steel structure change from concretes name: Temu Gelang structure of Soekarno’s idea as the structure is

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“the Indonesian Women in Floating in Space” created by Soerono. Behind the interior of the walls of dome, it is filled the mosaic-art created by Darta’s name “A Dance of Indonesia”. There are also found the realist painting of Indonesia, Lie Man Fong in “the Indonesia Flora and Fauna”. The diversities artworks displayed at the Hotel Indonesia resembles the “Stage of Indonesian Fine Art”. Fig. 4 shows Hotel Indonesia building proposed by Abel Sorenson. 3.5 The Istiqlal Mosque The Istiqlal Mosque is the largest mosque in Indonesia and it is the Soekarno’s idea in 17 years before the first pole in 1961, built as the victory symbol

designed to follow the athletic activities pattern to track continuously by the oval geometric shape. Soekarno also put the ornaments of a realist sculpture of mythical puppet Sri Rama to make it still be an archery as the symbol of precision, agility, honesty. The Gelora Bung Karno resembles a “architecture stage” of Indonesia of Soekarno’s politician will. The Main Stadium Gelora Bung Karno Gedung Pola building is proposed by Russian architect (Fig. 3).

Fig. 2

The “Gedung Pola” building.

Fig. 3

The main stadium Gelora Bung Karno.

3.4 The Hotel Indonesia Building In the front of hotel, it is located of statues and a pool covered with a red lotus pond named Henk Ngantung Fountain, and the welcoming to the young men and women statue carrying a bouquette of flowers, known as the Welcoming Statue as Edhi Soenarso’s work to visualize Soekarno’s idea to give the friendliness impression of Indonesian to the foreign guests. Soekarno asked Abel and Windy Sorenson, a couple architect to express his desire, and adopted all of the name of the islands and the dance’s name in Indonesia as the room’s name. Soekarno ordered a variety of Indonesian artists to beautify the building façade. A long andesite rock is created by Harijadi entitling “The party in Bali” opposite the statue of Goddess Sri created by Trubus. Under the Ramayana’s big dome, it is found the reliefs color

Fig. 4 Hotel Indonesia building proposed by Abel Sorenson.

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The Idea of “Architecture Stage”: A Non-material Architecture Theory

of the Indonesian independence. The visual images of mosque are dominated by the prime marble and stained less steel, reinforced concrete structure with the square pillars rhythmically across the facades. The building with the giant dome is as a marker of the grandeur to the Moslem’s with a tall minarets in the corner’s building and as a symbol of the immaterial at least for 1,000 years. The Istiqlal Mosque designed to express the modern architecture style with the solid structure and rely on the natural ventilation. Fig. 5 shows the Istiqlal Mosque building proposed by Silaban.

Centre. The presence of the Wisma Nusantara provided the quality space at the Hotel Indonesia which resembles the Modern Architecture’s style, and it is funded by the Japanese government. At that time the first skyscraper in Jakarta is also projected as the tallest building in Asia. Fig. 7 shows Wisma Nusantara Building. 3.8 The Sarinah Department Store The Sarinah Department Store now has undergone changed all of the facades. Sarinah building is Soekarno’s

3.6 The National Monument The National Monument or Tugu Nasional is located in the center of the Medan Merdeka square. Yet, it is known as the Champ de Mars or Koniengsplain. It was built to express the “new soul of Indonesian” as the dynamic nation in the modern age. The monument is designed by National Competition and held in twice, in 1955 and 1960, and the both competitions have not been found the ultimate winner, because its Soekarno is ordered to Silaban and Soedarsono to develop the idea from the first and second contest participants as a Final Design Project. Finally, the Soedarsono’s design is accepted by Soekarno. He design a pair of the giant cup and phallic as the monument’s form and as the ancient artifact symbol of Indonesia: lumpang and alu.. Refers to Lobell’s theory of Spatial Archetype, the monument shows the Radiant Axes civilization as Soekarno’s unconscious as ruler. He reflected “the world of emperor” linked with civilization, space and psyche. Fig. 6 shows the national monument.

Fig. 5

The Istiqlal Mosque building proposed by Silaban.

Fig. 6 The national monument proposed by Soekarno himself visualized by Soedarsono.

3.7 The Wisma Nusantara Building The Wisma Nusantara is 29 levels high building to facilitate the economic relations, trade and international tourism in Jakarta. The building is designed by Ciputra, which is as the first skyscraper in Indonesia role and as the building Trade and Travel

Fig. 7 The Wisma Nusantara Building proposed by Ciputra.

The Idea of “Architecture Stage”: A Non-material Architecture Theory

idea triggered the establishment of economic growth as shopping, exhibitions, and office building also has an important meaning as the price stabilizer. The building is calculated by Roosseno’s engineer, covered by ceramic materials, and floored by marble and framing door and windows by aluminum. The building is used the vertical transport escalators as the first in Indonesia, reflected the new of life style during in 1960s, and it is resembled the Indonesian merchandise selection, ranging from food and clothing as the modernities of Indonesia. Fig. 8 shows the Sarinah Department Store Building.

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3.9 The Planetarium Building The planetarium designed as the largest in the world, within 500 people seats as an educational building to understand the aerospace science, to eliminate the superstitions of Indonesians by activities with observatory of the astronomy which is the progressive symbol when it was still overwhelmed with superstition regarding astrology. The building shows the atmosphere of space to watch the stars and the solar motion through a comfortable room. Fig. 9 shows the Planetarium proposed by Ismail Sofyan and Ciputra. 3.10 The Conefo’s Political Venue Building

Fig. 8

The Sarinah department store building.

The Soekarno’s ideas to the “New World Order” concept are visualized by the venue’s design to the Conference Building of Conefo on August 1966 (but nevertheless done). The Conefo’s competition is held in November 1964, won by Soejoedi Wirjoatmodjo and supported by Sutami. He present a full scale of architecture model in the unique simetrical dome as the aircraft wing and as a unique magnificent work. Fig. 10 shows the Conefo’s Building proposed by Soejoedi.

4. Conclusions

Fig. 9 The Planetarium proposed by Ismail Sofyan and Ciputra.

Fig. 10

The Conefo’s Building proposed by Soejoedi.

Soekarno’s architecture tacitly expressed his architectural knowledge in the manner of “eastern meets western” and he has given “color” as sense of presence in the ideas of the “architecture stage” by exploring Ancient Javanese form as the basic design of Modern Architecture, and refers to Lobell’s theory, the national monument’s symbol rays reveal the Soekarno’s unconscious of the produce the civilization and space linked with his psyche. The hidden meaning of the Soekarno’s concepts of space was found: The national monument not merely is a physical immortality of architecture landmark, but also reflects the “timeless of the immortal immateriality” by Soekarno’s voice recording at the Amphitheater Room and also reveal the ide “architecture stage”.

The Idea of “Architecture Stage”: A Non-material Architecture Theory

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P. Burke, The French Historical Revolution: The Annales Scholl 1929-1989, Polity Press, Cambridge, 1990. B.G. Glaser, A.L. Strauss, The Discovery of Grounded Theory: Strategies for Qualitative Research, Adline Transaction, London, 2010. Y. Ardhiati, The stage of Indonesia: Khora charm works

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of “Architect” Soekarno in the 1960s, Dissertation Thesis, Department of Architecture, Faculty of Engineering, University of Indonesia, 2013. A.G. Perez, S. Parcell, Chora 1, 2, 3: Intervals in the Philosophy of Architecture, Mc Gill Queen’s University Press, London, 1994. J. Derrida, On the Name, Stanford University Press, California, 1995.