EPS as an Inclusion Material: An Instrumented Field Study on Retaining Wall

Retaining walls are designed considering lateral pressure acting on the walls due to retained backfill, traffic and seismic loads, etc., and the reduction in the lateral pressure exerted on the wall would lead to a reduction in construction costs. The provision of a compressible inclusion between the wall and backfill changes the stress state in the retained wall, resulting in a significant reduction in lateral pressure on the wall. Expanded polystyrene (EPS) geofoam is a suitable inclusion material due to its lightweight, predictable stress–strain response, availability, and ease of installation. Though several studies were reported on the use of EPS geofoam to reduce earth pressures on retaining walls, most of the studies were based on small-scale model tests, and understanding the effect of EPS geofoam through full-scale instrumented studies is very essential. In the present study, fully instrumented field tests are conducted to check the suitability of EPS as an inclusion material to reduce the earth pressures on a rigid reinforced concrete cantilever retaining wall. A wall of 6 m in height and 8 m in length is constructed, divided into two sections of 4 m each. Each section is instrumented with earth pressure cells (EPC) for pressure measurement. A 250 mm thick EPS15 inclusion is used in one section, and in another section, no inclusion is placed. The response of EPC in both sections is continuously monitored during the backfilling process. The results clearly show significant differences in the response of EPC on sections with and without geofoam.