The application of EPS geofoam in mitigating the approach problems in integral abutment bridges

The present thesis aims to extend an insight into the soil-structure interaction behaviour in the Integral Abutment Bridge (IAB) with particular emphasis to the soil settlement and the lateral pressure issues at bridge approaches. It then investigates the effectiveness of the expanded polystyrene geofoam (EPS) in mitigating these effects. Physical modelling together with numerical analyses have been utilized to perform these investigations. A finite element model, first, developed using ABAQUS/standard software and used to simulate, in prototype dimensions, a wide-base embedded abutment experiencing cyclic movements as would be anticipated to occur in IABs. The model was validated using centrifuge test results from previous literature and employed to perform a parametric study on the dominant factors affecting the soil-abutment interaction behaviour. An experimental program then carried out to investigate the influence of the mode of wall movement, rotation or translation, and the effectiveness of the EPS geofoam inclusion using a physical model of a small wall retaining loose sand on one side. The experimental test results of the small wall were used to validate a finite element model that incorporated an EPS geofoam inclusion. The EPS behaviour was simulated using a hyper-foam constitutive model and calibrated using the laboratory test results. Following which, finite element modelling was applied to investigate the impact of using EPS geofoam inclusion in prototype dimensions on the soil settlement and lateral earth pressures in IABs. Different geometrical arrangements for the EPS inclusion have been investigated and conclusions about the optimum EPS arrangements have been given. Finally, the research conclusions and recommendations for future studies in regard to the soil-structure interaction behaviour in IABs and the possible remedy measures using the EPS geofoam are presented