Bridge approach settlement mitigation using expanded polystyrene foam as light backfill: Case study and 3D simulation

This paper presents the behavior of the bridge approach structure, which was repaired by using expended polystyrene foam as a replacement fill on Soft Bangkok Clay. The bridge approach began construction 20 years before a project. The settlement from consolidation and ground subsidence was high at 1.35 m at the end of the bearing unit before remedial measures. The settlement of the bridge approach structure before the project began and after completion was presented. After remedial measures, settlement rates tend to decrease after 100 days. The behavior of the bridge approach structure was modeled by using finite elements. The time-dependent strain of EPS geofoam can be predicted by an empirical equation by optimizing method. 3-dimensional finite element analysis can predict the overall behavior of bridge approach structure using EPS as fill material with time dependent stiffness. The prediction before and after remedial measurement of the embankment was using similar model parameters. Important considerations to simulate EPS embankment behavior were long-term stiffness degradation of EPS block and ground subsidence.