DEM analysis of small and small-to-medium strain shear modulus of sands

Despite the significant progresses in discrete-based numerical studies of granular materials, most efforts have been placed in the study of large deformation problems and there are many unresearched areas in the multi-scale analysis and the influence of grain-scale parameters on the bulk behavior of granular systems in the regime of small strains. In this work, we present a numerical investigation into the small and small-to-medium strain shear modulus of sands performing DEM analyses, exploring the influence of grain-scale parameters, and attempting to link micromechanical-based quantities with the macroscopic behavior of granular materials. For the calibration, we used real experimental grain-scale data for the contact stiffness and interparticle friction, and resonant column macroscopic test results on a quartz sand were used as the benchmark model sample. Subsequently, a parametric DEM study was carried out investigating the influence of Young's modulus (and contact stiffness) as well as the interparticle friction on macroscopic stiffness and stiffness reduction curves, and additional insights were obtained based on the inferred contact forces and force networks, coordination number and fabric anisotropy. The numerical results contribute to understand the differences between different sand types as reported in the literature in the regime of small-to-medium strains.