A particle model for rockfill behaviour

Abstract

Particle crushing has been introduced into a discrete model for rockfill aggregates by a novel approach which combines a closed-form solution for stress distribution inside particles and a crack propagation criterion derived from fracture mechanics concepts. Two breakage modes are simulated: a local contact crushing and an equal volume splitting. The occurrence of both modes derives from experimental observations. Three main parameters control the model performance: contact stiffness, basic friction angle of the particle material and the particle toughness. Contact stiffness and friction were determined by experiments. A large diameter oedometer test on hard limestone gravel was successfully simulated. The simulation included the prediction of the compression response and the evolution of grain size distribution. Rock toughness and basic friction angle were determined independently from the oedometer results. Subsequently, large-scale triaxial tests on the same material and different grain size distributions were simulated. Model parameters fitting the oedometer test were maintained unchanged. The predicted triaxial response (deviatoric stress–strain response, volumetric behaviour and final grain size distribution) was close to actual measurements.