PROJECT: USE OF DRY STONE RETAINING WALLS FOR URBAN DEVELOPMENT WORKS IN PERU

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