Level Set Discrete Element Method Modeling of Naturally Deposited Sand in Triaxial Compression

Level-set discrete element method (LS-DEM) is used to model the triaxial compression of naturally deposited sands reconstructed from X-ray computed tomography (XRCT) images with different resolutions. Triaxial test simulations with flexible membrane give results that capture the observed stress–strain and volumetric response as well as the onset and growth of strain localization. The simulation results also match experimentally observed relationships between the deviatoric stress and the mobilized friction angle as axial shortening increases and the cyclic unload-reload behavior. The results show that the main source of mobilized strength is the geometric arrangement of the particles, the fabric, and the resulting mechanical interlocking between irregularly shaped grains. Moreover, the results show that even the simplest contact model gives results consistent with the micro- and macro-mechanical response observed in the experimental data, provided the microstructure of the grains and grain-to-grain contacts is accurately captured.