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

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.