Study of evolution of sand crushability based on discrete elements method

Detailed knowledge of crushability evolution and particle-scale energy allocation behavior under the influence of particle breakage is of fundamental importance to the development of micromechanics-based constitutive models of sands. This study reports original results of the particle development, energy input/dissipation and shear band formation of idealized crushable sands using 2D discrete elements simulations. Particle breakage is modeled as the disintegration of synthetic agglomerate particles which are made up of parallel-bonded elementary discs. Simulation results show that the particle crushability strongly affect the mechanical response in macroscopic level and energy allocation in particle-scale level of the soil both at small and large strains. The major role of particle breakage, which itself only dissipates a negligible amount of input energy, is found to advance the soil fabric change and promote the inter-particle friction dissipation. At large strains where particle breakage is greatly reduced, a steady energy dissipation by inter-particle friction and mechanical damping is observed. Furthermore, it is found that the amount of particle breakage keeps increasing during the whole shearing process; but the rate of particle breakage decreases gradually with the applied axial strain. And a clear shear band can be found in low-crushable soil and the anisotropy of the broken bonds becomes weaker and weaker as the development of shearing.