Discrete simulation and micromechanical analysis of two-dimensional saturated granular media

In this study,a novel approach to incorporate the pore water pressure in the discrete element method(DEM) to comprehensively model saturated granular media was developed.A numerical model was constructed based on the DEM by implanting additional routines in the basic DEM code;pore water pressure calculations were used with a two-dimensional(2D) model to simulate the undrained behavior of saturated granular media.This model coupled the interaction of solid particles and the pore fluid in saturated granular media.Finally,several 2D undrained shear tests were simulated.The test results showed that the model could predict the response of the saturated granular soil to shear loading.The effect of initial compaction was investigated.Biaxial tests on dense and loose specimens were conducted,and the effect of the initial density on the change in shear strength and the volume change of the system was investigated.The overall behavior of loose and dense specimens was phenomenologically similar to the real granular material.Constant volume tests were simulated,and the results were compared to those from the coupled model.Induced anisotropy was micromechanically investigated by studying the contact force orientation.The change in anisotropy depended on the modeling scheme.However,the overall responses of the media obtained using the coupled and constant volume methods were similar.