Discrete element simulations of direct shear tests with particle angularity effect

Abstract

This paper investigated the effect of the particle angularity in light of its importance in angular particle assemblies, using the discrete element method (DEM). A discrete element model with a general contact force law for arbitrarily shaped particles was developed, in which angular particles were modeled using convex polyhedra. Quasi-spherical polyhedral shapes with different vertexes were adopted to reflect the change of angularity. Four categories of assemblies with different angularities were generated. A series of direct shear tests performed on these assemblies were simulated at different vertical stresses. All numerical implementations were achieved using a modified version of the open source DEM code YADE. It was found that the macroscopic shear strength and dilatancy characteristics are in agreement with experimental and numerical results in the literature, indicating that the present numerical model is reasonable. Besides, the evolutions of coordination number, normal contact force distribution, and anisotropies of particle orientation and contact normal were investigated. The results show that the angularity plays a vital role in strengthening the interlocking of angular particles.