RESEARCH ON

GEOTECHNICAL

EARTHQUAKE IN THE

HUMAN SETTLEMENT

OF LIMA-PERU

RICARDO PALMA UNIVERSITY

FACULTY OF ENGINEERING

CIVIL ENGINEERING

RESEARCH INSTITITUTE

RESEARCH ON GEOTECHNICAL EARTHQUAKE IN THE “HUMAN SETTLEMENTS” OF LIMA -PERU ADVISERS: Dr. ARNALDO CARRILLO GIL Ing. OSCAR DONAYRE CORDOVA

1. INTRODUCTION

With field explorations and the obtained information from surveys made by the students, many places were identified where common construction of “pircas” were used. A model was developed in order to analyze their static and seismic conditions, considering the earthquake magnitude according to the site seismic recurrence and building characteristics as well as their risk and vulnerability due to more common disasters.

Typical foundations on “pircas”

A typical case of slope failure was considered in order to determine through back analysis and test in situ, the resistance average parameters to shear strength. Data was evaluated on laboratory, in a real scale prototype with the geotechnical site conditions. In addition, geological characteristics of the site were also considered.

Geotechnical model

In situ model of “pircas” foundation 2. GEOTHECNICAL CONDITIONS

In the field were made penetration tests and exploration pits and then tested in the laboratory each soil sample extracted. From a statistical standpoint, the survey of a sample of the population of the area to evaluate the situation and / or condition of building their homes and the behavior of people in an earthquake

Field Works

3. METHODS FOR GEOTHECNICAL DESIGN

3.1 Slide 5.0

Slide 5.0 is a 2D program Slope stability to evaluate the stability of circular or no circular failure surfaces of soil or rock slopes. You can create complex models, modeling external loads, groundwater and supports a variety of ways. 3.2 Slope/W

El software Slope/W is a product tha use the balance limit to calculate the security factor on earth and rock slopes. Slope/W has an application for the analysis and geothecnical, civil design, and projects of mine engineering. 3.3 MacStar 2000

The program MacStar 2000 has been developed to verify the stability of reinforced soil, which are structures that provide stability on a slope using units of reinforcements that can absorb tensile stress.

4. MODELING OF THE COLLAPSE AREA

It took the dimensions and characteristics of the house collapsed as shown in the following figure.

Measurements of the collapse

5. CALCULATION OF THE PARAMETERS OF SHEAR STRENGTH OF SOILS

In this study the calculation of these parameters was made by the Method of retro Analysis because there was no such information at the moment of the collapse.

Screen of Slide 5.0 showing one of the safety factors

6. SEISMIC ACCELERATION COEFFICIENTS

For the particular case of the software you need to have additional data seismic acceleration coefficients, horizontal and vertical, especially for the analysis of the model under dynamic condition.

Seismic acceleration coefficients

Horizontal 0.15

Vertical 0.072

7. DISCUSSION RESULTS

Results show safety factors that are lower than 1, and significantly lower in case of an earthquake of shallow acceleration of 0.30g and magnitude of 7.5Mw, values which point out that it is not necessary an earthquake to cause slides on the foundation. Because of these results, it is essential to check for practical and economical solutions in order to avoid material and human losses (Figure 8). The progress of these studies allows us to establish the construction process in walls, platforms, and foundations.

8. CONCLUSSIONS AND RECOMMENDATIONS 1. The failure rate of housing

construction in these settlements is really alarming because of the lack of supervision or technical criteria.

2. The vulnerability of households in most human settlements because they are located on hill slopes, with a foundation inappropriate, a very steep slope and with materials that do not guarantee static and dynamic stability of the building.

3. This vulnerability is directly related to the safety factors calculated by different methods that have been presented, the same as determining whether an area is stable or not.

4. “Human Settlements” those are most vulnerable due to the high recurrence of the use of stone walls.

5. The survey techniques found in each field work demonstrate the absence of information to the residents of these sectors has on the direct or indirect damages that result in a collapse.

6. This paper has complied with its commitment to demonstrate the vulnerability of this type of existing foundations type Pirca.

REFERENCES

– Braja M. Das, “Principles of Foundation Engineering”, Fourth Edition.

– Carrillo Gil, Arnaldo “Geotecnia de los Suelos Peruanos” Instituto Peruano de Ingeniería Geotécnica y Geoambiental, Lima, Perú.

– Carrillo Gil, Arnaldo, “Peligro sísmico en los Barrios Marginales del Sur”, Conferencia Instituto Peruano de Ingeniería Geotécnica y

Factor of Safety

Factor of Safety

Method

Condition

Static Seismic

Slide 5.0 0.913 0.755

Slope/W 0.847 0.712

McStar 2000 0.911 0.701

Geoambiental, CIP, CDL, Lima, Perú.

– Carrillo Gil, Arnaldo “Education and Practice: The Peruvian experience” 17th International Conference on Soil Mechanics and Geotechnical Engineering, Alexandria, Egypt.

– Donayre, Oscar, “Evaluación del Comportamiento de los Suelos Granulares Finos del Sur de Lima Metropolitana”, Tesis de Grado Universidad Ricardo Palma.

– Hoek, Evert, “Hoek – Brown Failure Criterion”, Edición 2002, pag. 1-7.

– Juárez Badillo, Rico Rodríguez, “Mecánica de Suelos”, Tomo 1 Editorial Limusa S.A.

– Kramer, Steven L., “Geothecnical Earthquake Engineering”, University of Washington, Prentice Hall, New Jersey, Cap. 11, pags. 466 – 505.

– RocLab, User’s Guide, pags. 1 – 27.

– Sandoval, Israel, “Evaluación Geotécnica y Sísmica de los Asentamientos Humanos del Norte de Lima Metropolitana”, Tesis de Grado Universidad Ricardo Palma.

– Slide 5.0, “2D Limit Equilibrium Slope Stability for Soil and Rock Slopes”, Manual de Usuario, Cap. 1 y 2, Rocscience Inc.Slope/W, User’s Guide.

– Torres, César, “Valoración del Riesgo en Deslizamientos”, Tesis de Grado Universidad Ricardo Palma..

– Whitman, Robert V., “Dynamic Behavior of Soils and its Application to Civil Engineering Projects”, Sixth Panamerican Conference on Soil Mechanics and Foundation Engineering, Lima – Perú.

– Whitman, Robert V., “Limiting Cases for Distribution of Lateral Stress, Sixth Panamerican Conference on Soil Mechanics and Foundation Engineering, Lima – Perú.