Discrete Element Analysis of Idealized Granular Geometric Packing Subjected to Gravity

This paper presents discrete element analysis models for studying quasi-static stress states in idealized granular materials subjected to gravity, and utilizes geometric packings and contact mechanics. The theoretical description of granular materials in assemblies of microscopic particles is a challenging task. The particle assemblies characterize in-situ initial and boundary conditions. In turn, the conditions are used in solving the equations of motion of the particulate system under stress equilibrium states (via a network of particle contact forces and various degrees of dissipative interparticle friction). Using the discrete element analysis model of LS-DYNA [1], the influence of packing on contact stress distributions within an explicit time domain is investigated using idealized assemblies of spherical discrete elements and contact penalty springs. The validity of idealized geometric packings, as to whether uniformity can simulate granular fabrics, is still a matter of debate. However, the present study strictly focuses on the effects of micromechanical structures (idealized by assemblies of spherical discrete elements) in stress states at a macroscopic scale. In this context, the macroscopic scale is associated with the size of samples used for direct shear experiments in laboratory settings).