Effect of Long-Term Performance of EPS Geofoam on Lateral Earth Pressures on Retaining Walls

This paper presents short- and long-term influence of EPS geofoam to reduce static and traffic loading induced earth pressures on non-yielding rigid retaining walls. Grade III Indian standard sand and EPS15 geofoam (15 kg/m³ density) are used in model studies, as backfill and compressible inclusion at the interface between the retaining wall and backfill, respectively. Short- and long-term static and traffic loading model tests are performed with and without presence of geofoam. Model retaining wall is instrumented with pressure sensors to measure the lateral earth pressure on wall. Plastic markers are placed along the width of model plate, geofoam, and sand backfill to measure the movement of wall, geofoam compression, and backfill settlement, respectively. Compressive creep (CC) strains of 3% are induced on geofoam samples to simulate pseudo-long-term (PLT) behavior of geofoam. Static and traffic loads are applied on backfill using Servo-hydraulic actuator and surcharge load distribution system. Lateral thrust isolation efficiencies of 55.1–64.2% and 60.6–69.4% are observed under static and traffic loading conditions, respectively, in the presence of geofoam. Higher lateral thrust isolation efficiency, geofoam compression and backfill settlements are observed from the pseudo-long-term static and traffic loading on retaining wall compared to respective initial tests.