Particle Shape Effects in 3D DEM Simulations of Angle of Repose

Crushed rock is a common granular material in civil engineering, mining, and railway applications. Numerous prior studies have shown that design-scale mechanical behavior strongly depends on the morphological features of the particles. In this study an efficient technique to import realistic particle geometries into DEM simulations of bulk granular materials is provided. First, a suite of 300 synthetic 3D particle geometries (referred to as particle avatars) of varying sizes and shapes is prepared using a computational physics engine. Second, relationships between widely used 2D and 3D shape descriptors are obtained for the particle avatars. From the 2D-3D shape relationships it is observed that the true sphericity (3D) is well correlated with perimeter sphericity (2D). Therefore, some 3D shape features can be reasonably estimated from 2D digital images of grains. Finally, DEM simulations are carried out to investigate angle of repose for several clump geometries. The bubble pack technique was used to create pebble clumps with varied numbers of pebbles. Results show that the repose angle is more strongly dependent on the shape of the created clump (collection of pebbles) than by the shape features of the original particle geometry. This research shows that the shape features of the clumps used in simulations affect the results, regardless of the procedures used to get 3D geometries of particles.