Micromechanical study of particle breakage in 2D angular rockfill media using combined DEM and XFEM

A micromechanical study of particle breakage in 2D angular rockfill materials under biaxial compression loading has been conducted using a combined DEM and XFEM approach. In this approach, modeling of the crack propagation is performed on a fixed mesh without the limitations of classic FEM. Each breakage analysis is based on the final crack propagation state in the previous step; therefore, the progressive strength reduction of the particle is incorporated into the breakage analysis during loading. The micromechanics of the non-breakable and breakable assemblies have been studied under different confining pressures. It was found that particle breakage reduced the voids in the assembly, which resulted in a decrease in the final displacement of the particle assembly. Also, the contact forces, particle stresses and anisotropies decreased as a result of particle breakage and a more uniform distribution of contact forces and stresses was created. It was observed, as the confining pressure increased, the particle breakage increased and its effects intensified. Particle breakage was found to be the main cause of the decrease in anisotropies at higher confining pressures which, consequently, led to a reduction in the friction angle of the assembly.