Lateral earth pressure of granular backfills on retaining walls with expanded polystyrene geofoam inclusions under limited surcharge loading

Existing studies have focused on the behavior of the retaining wall equipped with expanded polystyrene (EPS) geofoam inclusions under semi-infinite surcharge loading rather than limited surcharge loading. In this paper, the failure mode and the earth pressure acting on the rigid retaining wall with EPS geofoam inclusions and granular backfills (henceforth referred to as EPS-wall), under limited surcharge loading are investigated through two- and three-dimensional model tests. The testing results show that different from the sliding of almost all the backfill in the EPS-wall under semi-infinite surcharge loading, only an approximately triangular backfill slides in the wall under limited surcharge loading. The distribution of the lateral earth pressure on the EPS-wall under limited surcharge loading is non-linear, and the distribution changes from the increase of the wall depth to the decrease with the increase of the limited surcharge loading. An approach based on the force equilibrium of a differential element is developed to predict the lateral earth pressure behind the EPS-wall subjected to limited surcharge loading, and its performance was fully validated by the three-dimensional model tests.