Numerical Analysis of Earthquake Load Mitigation on Rigid Retaining Walls Using EPS Geofoam

Deling Wang,Richard J Bathurst

doi:10.2174/1874149501206010021

Abstract

The mitigation of seismic-induced dynamic earth forces by placing a vertical layer of expanded polystyrene (EPS) geofoam buffer between a rigid retaining wall and the backfill soil is a recent geotechnical innovation. In this paper, the influence of an EPS geofoam buffer on the reduction of dynamic wall forces is numerically studied by simulating the results of three reduced-scale models of rigid walls mounted on a large shaking table. Numerical simulations were carried out using the finite element program ABAQUS. The paper shows that the numerical results capture the trend in earth forces with increasing base acceleration for all three models. The quantitative dynamic load-time response from the numerical simulations was also judged to be in good agreement with measured physical test values. The numerical trend of EPS geofoam also is the same as that of measured test data. With the increasing time, the compression of EPS geofoam increases. And softer EPS geofoam produces more compression which takes more vibration energy by its deformation. The numerical results confirm the results of physical tests that demonstrate that EPS geofoam seismic buffers hold great promise to reduce earthquake-induced dynamic loads against rigid retaining wall structures.

Highlights

Expanded polystyrene (EPS) geofoam is a lightweight polymeric material which is made by expansion of raw plastic beads
Gaskin [2] and Bathurst et al, [3] carried out reducedscale shaking table tests on a rigid retaining wall protected by EPS geofoam
The physical tests described in this paper were carried out on a 2.7m2.7m shaking table located at the Royal Military College of Canada (RMC)

Summary

INTRODUCTION

Expanded polystyrene (EPS) geofoam is a lightweight polymeric material which is made by expansion of raw plastic beads. Inglis [1] reported the first use of EPS geofoam as a seismic buffer to reduce potential seismic earth loads against a non-yielding basement wall. Gaskin [2] and Bathurst et al, [3] carried out reducedscale shaking table tests on a rigid retaining wall protected by EPS geofoam. Researchers have used different numerical approaches to investigate the use of seismic buffers to protect retaining walls: a simple displacement-type block model [4], a. Results are compared to measurements from reduced-scale physical models of rigid walls with and without a geofoam seismic buffer

SHAKING TABLE TESTS AT RMC

NUMERICAL MODELS

NUMERICAL RESULTS

CONCLUSIONS