Numerical Study of the Influence of Foundation Soil on the Deformation Behavior of Geosynthetic Reinforced Soil-Integrated Bridge System under Service Load Conditions

The geosynthetic reinforced soil-integrated bridge system (GRS-IBS) is becoming widely used for transportation infrastructure. Most of the reported GRS-IBS case histories were constructed on relatively stiff foundation soil layer, and all showed good service performance. This paper presents a numerical study of the deformation behavior of GRS-IBS under service load conditions, with the objective of evaluating the influence of foundation soil conditions. Numerical simulations were conducted using the finite difference program FLAC for GRS-IBS constructed on granular foundation soils with different densities. The granular foundation soil and backfill soil were characterized using a nonlinear elasto-plastic model that incorporates the Duncan-Chang hyperbolic relationship and the Mohr-Coulomb failure criterion. Foundation soil parameters were selected according to data reported in the literature, and the soil stiffness and strength increase with increasing density. Geogrid reinforcements were characterized using linearly elastic-plastic cable elements. Various interfaces were included to simulate the interaction between different components. Simulation results indicate that increasing the foundation soil stiffness and strength effectively reduce facing displacements, bridge seat settlements, and foundation soil settlements, but also produce larger vertical compressions of the GRS abutment. Results provide insights for the application of GRS-IBS for different granular foundation soil conditions.