USE OF DRY STONE RETAINING WALLS FOR URBAN DEVELOPMENT WORKS IN PERU Sandra Santa-Cruz, Dominique Daudon, Nicola Tarque Graciela Fernández de Córdova, Marta Vilela Research assistants: Criss Zanelli, Gram Rivas, Elliot Quispe, Vladimir Ramos, Anghie Parraga, Julio César Alcántara GERDIS
The occupation of sloped lands in the highlands has been well managed using ancient techniques with Dry Stone Retaining Walls
Terraces PIRCA
Cuzco-Peru Source : Kendall, A., & Rodríguez, A. (2009). DESARROLLO Y PERSPECTIVAS DE LOS SISTEMAS DE ANDENERÍA DE LOS ANDES CENTRALES DEL PERÚ. (Institut Francais d’études Andines & Centro de Estudios Regionales Andinos Bartolomé de las Casas, Eds.)
GERDIS
The Informal occupation of steep slopes in urban areas is trying to resemble traditional dry stone retaining walls called PIRCAS 2.5 million people in Lima live in these conditions
Vivienda Dwelling Relleno Backfill Pirca Pirca
GERDIS
“Lomas�
The objective is to analyze the risk factors of pircas and discuss opportunities Data Gathering
Resilience
• Accesibility • Land use planning • Risk perception
Fragility
• • • • •
Factor Analysis
• Earthquake • Runoff
Natural Hazards • • • •
Discussion
GERDIS
Material Geometry Type Quality Failure Mode
Sustainability Economic Environmental Social
• Interview • Participative workshops • • • • • •
Local workers interview Visits Laboratory test Previous data Rules and Codes Review Full scale testing
• Probabilistic Approach
• • • •
Strength Weaknesses Risks Opportunities
Pircas are made of angular shaped stones fitted in a three-dimensional jigsaw
Void percentage is 15 % for walls composed of long stones and 25% for walls composed by small blocks (Villemus, 2013)
limeston
Limestone wall (McCombie, 2016) TIPO DE ROCA 1. Redonda
Source: NGO Soluciones Prรกcticas
2. Angular
3. Cuadrada
1% 3%3%
93%
GERDIS
200- 500 mm
4. Otros
Geometry European heritage. H= 2 - 4 m up to 10 meters H =3 m on average (McCombie, 2016)
H = 0.5m - 3m
GERDIS
Construction process
Trench
Shakti el al (1997)
GERDIS
Mc Combie 2016
Both wall construction techniques have some elements in common Pircas
European
Through stone
DSWA (2011)
WHE EERI
GERDIS
Bothara & Brzev 2011
Design
Guidelines for analysis of existing structures
Peru has no regulatory framework for pircas assessment or design
Associations
USA fhwa-flp-cfl/td-06-006 Rockery Design and Construction Guidelines UK CS 454 Assessment of Highway Bridge and Structures Construction Industry Research and Information Association CIRIA-676 Dry stone Retaining Walls and their Modifications-Condition Appraisal and Remedial Treatment (2009) Dry Stone Walling Association (2011) Section 04600 Dry stone wall retaining system India Code IS 14458 (Part 3) ENTPE France design charts
UK, France, Australia, USA
GERDIS
Guidelines
MML (Municipalidad de Lima), 2013. GuĂa para la habilitaciĂłn urbana en asentamientos humanos. Lima.
We tested 6 pircas of h= 1.0 and 1.5 m built by two pircas builders 2 hydraulic pistons 1 hyd.pump. 2HP Electronic control panel. (30 A, 220 V)
Tilting platform
Theodolite Control panel
H (m)
Colas et al, 2010
Average
Average
Collapse
Capacity/W
angle(ยบ)
H= 1m
GERDIS
H = 1.5 m
18
31%
14
25%
The use of through stones could improve the stability of the cross section delamination
Through stones
Meyer et al 2007
Colas et al, 2010
GERDIS
Out-of-plane deformations Catenary action (plan view)
Mc Combie 2016
Deformation
Bending
shear
bending + shear
Colas 2016 120
100
80
H
60
40
20
0 0
GERDIS
10
20
30
Out of plane displacement
The approximate total cost is 100 USA dollars per meter
unit
Rock preparation hh Wall hh Backfill m3 Total
GERDIS
#
Unit cost 5 6a8 1.5
6.25 6.25 10
subtotal 31.25 50 15 96.25
PIRCAS are perceived by the population as a possibility to use as a part of their urban landscape to protect and to limit
GERDIS
Using PSHA, we found that the capacity is smaller than the forces for an occasional earthquake PGA (g) Tr=475 years 1.00
Occasional earthquake, TR= 72 years Carabayllo
H 0.38
H
PGA*: con amplificaciรณn
Level
PGA (g)
Frecuente
0.18
0.22
Ocasional
0.22
0.27
Raro
0.42
0.51
GERDIS
topogrรกfica (x1.2)
1m 1.5 m
Demand Capacity (% Weight) % ( Weight) 29 32
High risk
31 25
-Low Cost
-Ecosystem services
-Informality
Risk
GERDIS
-Limited accessibility and connectivity
-Lack of maintenance
-Use as limit of protected natural areas
-Uncertain Seismic performance
-Strengthen capabilities for social inclusion
Disadvantages
-Low CO2 emission
-Periodical inspections
Opportunities
Advantages
There is a need for skilled manual labor to increase the seismic performance and capacitation
Thank You
Acknowledgement • 109-2017-FONDECYT • Municipalidad de Carabayllo • Municipalidad de Villa María del Triunfo • ONG Soluciones Prácticas • ONG Medlife GERDIS
