Discrete numerical modelling of single-particle crushing and oedometric tests, for different values of suction

Abstract

Particle breakage plays an important role in rockfill mechanical behaviour. Under compression or shear, the crushing of particles modifies the grain size distribution and indirectly, the material permeability, their frictional properties and the corresponding critical state. In order to study the breakage of individual particles, several approaches were adopted using discrete element method (DEM). Some considered sub-particles joined by bonding or cohesive forces, other replaced particles, which verified a predefined failure criterion, by an equivalent group of smaller particles. In this paper, using the discrete element method, a new methodology was developed. It consisted of modelling crushable rockfill particles using the clump logic, which was responsible for providing a statistical and spatial variability in the strength and shape of the particles. Particle movements and interactions were determined using DEM, allowing to determined the deformation of the rockfill material. Clumps have a major advantage of severely decreasing the number of contact equations to be solved in the model, resulting in less computer time. A comprehensive study of the brittle failure of single-particle crushing tests is presented. Preliminary tests on particle size evolution were also performed, assuming some simplifications. No attempt was made to simulate the real particle size distribution (PSD), due to the cost of simulating smaller particles. Single-particle crushing tests and oedometer tests were simulated using crushable particles, whose results were in agreement with experimental data.

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