A Numerical Study on the Role of EPS Geofoam in Reducing Earth Pressure on Retaining Structures Under Dynamic Loading

The magnitude of lateral earth pressure plays an important role in the analysis and design of earth retaining structures. Expanded polystyrene (EPS) geofoam panels have been successfully used in reducing lateral thrust on walls under static loading condition. The presence of geofoam panels between a rigid wall and the backfill soil allows for controlled deformation to develop, which leads to the mobilization of soil shear strength. When subjected to dynamic loading, the magnitude of earth pressure acting on a rigid wall can become significantly larger. In this study, a finite element model is developed to investigate the effectiveness of installing geofoam buffer behind a rigid retaining wall on the seismic lateral thrust induced by the backfill material. A parametric study was then conducted to investigate the effect of geofoam density, relative thickness of the geofoam with respect to the wall height and the friction angle of the backfill soil on the effectiveness of this technique to reduce the impact of seismic events on the stability of the wall. Results showed that provision of geofoam behind rigid non-yielding retaining wall can provide 10-40% reduction in seismic thrust depending on the geofoam density, relative thickness and frictional properties of the backfill soil.