A Numerical Procedure for the Assessment of Contact Pressures on Buried Structures Overlain by EPS Geofoam Inclusion

Abstract

Extruded Polystyrene (EPS) geofoam is a light weight material used in a wide range of geotechnical engineering applications including embankment construction and bridge approaches to reduce earth loads imposed on the adjacent or underlying soils and structures. EPS is also used as a compressible material above deeply buried culverts to promote positive arching and reduce the load transferred to the walls of the structure. An important step towards understanding the soil-geofoam-structure interaction and accurately model the load transfer mechanism is choosing a suitable material model for the EPS geofoam that is capable of simulating the material response to compressive loading for various ranges of strains. In this study, a material model that is able to capture the response of EPS geofoam is first established and validated using index test results for three different geofoam materials. To examine the performance of the model in analyzing complex interaction problems, a laboratory experiment that involves a rigid structure buried in granular material with EPS geofoam inclusion is simulated. The contact pressures acting on the walls of the structure are calculated and compared with measured data for three different geofoam materials. The developed numerical model is then used to study the role of geofoam density on the earth loads acting on the buried structure. Significant pressure reduction is achieved using EPS15 with a pressure ratio of 0.28 of the theoretical overburden pressure at the upper wall. The proposed FE modeling approach is found to be efficient in capturing the behavior of EPS geofoam material under complex interaction soil-structure condition.