Discrete element simulations of dense packings and heaps made of spherical and non-spherical particles

The discrete element method (DEM) in the simulation of static packings allows one to investigate the behavior of granular materials by modeling the forces on the particle level. No macroscopic parameters like the angle of repose enter the simulation, but they can be extracted as a result of the particle properties like friction, roughness or shape. One of the issues of static packings recently discussed is the stress distribution under granular heaps. This problem is used to highlight the possibilities of modeling at the particle level using DEM. Phenomena like arching or stress-chains are observed even for spherical particles in a regular pile in the absence of friction if the bottom is rough. The situation does not change much if polygonal, frictional particles are used without disturbing the regular piling. For more realistic situations, when the pile is built by pouring grains from above, the packing and the stresses are influenced by the creation history. The more eccentric the polygons are, the more pronounced a dip is observed in the vertical stress under the apex of the sand-pile.