DEVELOPMENT OF EPS GEOFOAM TO REDUCE LATERAL PRESSURE BEHIND RETAINING WALLS

Abstract

Currently, there is a progressive move towards using Expanded Polystyrene (EPS) or Geofoam as an efficient alternative for partial soils backfills in several geotechnical applications. However, the shortage inaccurate material characteristics and limited design equations are considered as the main drawbacks of using EPS inclusions. In this research, a pilot study intended to characterize the engineering properties of the EPS and was initiated with the intension to develop a calibrated numerical model that is capable of solving somegeotechnical problems involving retaining walls with EPS inclusion. A comprehensive laboratory testing program was conductedin order to determine the strength properties of the local EPS.The interface properties between foam and other material such as concrete and sand were also measured. After laboratory testing, a finite element analysis using hardening soil constitutive model was utilized and calibrated to accurately capture the stress-strain and interface characteristics of EPS in dry and wet conditions covering a wide range of contact stresses. Since EPS is a light weight material that can be used to reduce the lateral earth pressure behind rigid and flexible cantilever retaining walls, a finite element model was calibrated to simulate the behavior of rigid and flexible retaining walls with EPS inclusion. The reduced earth pressure (REP) and the zero earth pressure (ZEP) concepts were studied to determine the effect of soil arching on reducing the lateral pressure on flexible walls. Static loading conditions were considered to determine the reduction in the coefficient of lateral pressure withEPS inclusion. During modeling, the EPS material properties were used with partial resistance factorsthatweredeveloped as part of this study. Finally, a physical prototype was assembled in the laboratory to verify the finite element results. Major outcomes of this research can besummarized as follows: