Numerical Simulation of the Load Transfer Mechanism of a Geosynthetic Encased Stone Column Unit Cell under Embankment Loading

Abstract

This paper presents a numerical study to investigate the load transfer mechanism of a geosynthetic encased stone column (GESC) under embankment loading. The soils were modeled with a nonlinear elasto-plastic constitutive model incorporating a hyperbolic stress–strain relationship and the Mohr–Coulomb failure criterion. The geosynthetic encasement was modeled using a linearly elastic embedded liner element. Two interfaces were used to simulate the interaction between the geosynthetic encasement and the soils on either side. The validation of the numerical model was conducted using test data from vertical loading tests of the individual GESC installed in loose sand, including applied vertical stress–settlement curves and the circumferential strains profiles. Then, the influences of different design parameters on the load transfer mechanism of the GESC unit cell were investigated through a parametric study. Results indicate that the development of stress concentration ratio depends on the mobilization of tensile strains. The circumferential strains are significantly larger than the longitudinal strains, indicating that the circumferential tensile effect is dominant under embankment loading. The load transfer effect was gradually enhanced with increasing tensile strains. Increasing the geosynthetic encasement stiffness can be considered as an alternative to increasing the column infill friction angle in improving the load transfer effect.