Numerical Simulation of EPS Geofoam as Compressible Inclusions in Fly Ash Backfill Retaining Walls

For many years, expanded polystyrene (EPS) geofoam has been successfully used as construction material in the field of geotechnical engineering due to its wide variety of applications, such as compressible inclusion in retaining walls and lightweight fill material in embankments. The present paper describes numerical modeling results carried out on EPS geofoam as compressible inclusion in retaining walls subjected to strip surcharge loading. Three different densities of EPS geofoam - 15, 20, and 30 kg/m³ - were used as compressible inclusions. The shape of EPS geofoam compressible inclusions used in the present study is orthogonal, i.e., constant thickness with depth. For each density, three different thicknesses (50, 100 and 150 mm) were considered. In India, thermal power plants produce enormous quantities of fly ash as by-product. Fly ash disposal and utilization in an environmentally friendly manner is a major concern in India. This study also focuses on using fly ash as an alternative backfill material in retaining walls. The plane strain finite element simulation was carried out using commercially available Plaxis 2D software. The backfill fly ash and compressible inclusion EPS geofoam were modeled as linear elastic perfectly plastic materials with Mohr-Coulomb failure criteria. The numerical results indicate that EPS geofoam placed between the retaining wall and the backfill fly ash has a good effect on reducing the horizontal deformation of facing panel, backfill settlements and lateral pressure.