Laboratory investigation and theoretical analysis of lateral pressure exerted by expansive soils on retaining walls with expanded polystyrene geofoam block upon water infiltration

The lateral pressure exerted by expansive soils on retaining walls constructed with expanded polystyrene geofoam blocks (EXRW-EPS), upon water infiltration to saturation, is crucial for designing these structures. In this study, model tests were employed to examine the behavior of EXRW-EPS subjected to water infiltration, with concurrent monitoring of deformation and lateral pressure. The results showed that the compressive deformation of the expanded polystyrene (EPS) geofoam block facilitated swelling deformations of the backfilled expansive soil, effectively mitigating the lateral pressure experienced by the retaining wall. Upon saturation of the backfilled expansive soil, the total lateral force on the wall decreased by approximately 44% by the EPS geofoam block with a density of 12 kg/m³. A practical method for predicting the lateral pressure on EXRW-EPS upon water infiltration to saturation was developed based on the relationship between the EPS geofoam block and the backfilled expansive soil. The reliability of this method was corroborated by the model test results. Additionally, the effects of the density and thickness of the EPS geofoam block on the lateral pressure of EXRW-EPS were analyzed using the prediction method.