Stress-Dilatancy of Rounded and Angular Rockfill Materials

Abstract

Rockfill materials consist primarily of angular to subangular particles obtained by blasting rock or extracting rounded to sub rounded particles from river bed. The stress-strain (stress-dilatancy) behaviour of rockfill materials is affected by mineralogical composition, particle grading, size and shape of particles and stress level. Particle breakage has an important effect on strength and stress-dilatancy behaviour. Based on a large scale triaxial tests data reported in literature, the stress-dilatancy relationship is analysed using Frictional State Theory. It is shown that stress level significantly influences the stress-dilatancy relationship. The double-effect of particle breakage may be observed: one − the energy consumed for breakage during shear, and the other − the extra contraction caused by breakage. Parameter α of Frictional State Theory represents the energy consumption effect and β represents extra contraction caused by breakage. It is shown that Frictional State Theory can reflect the influence of particle breakage on stress-strain behaviour of rockfill material.