Particle crushing and deformation behaviour

Particle crushing occurs in granular materials in various engineering applications. The effect of particle crushing is to broaden the grading of particle sizes and lower the critical state line and other characteristics of the volumetric response in the compression plane. An existing constitutive model, Severn-Trent sand, in which the critical state line plays a central role, has been extended to include the effects of particle crushing. Severn-Trent sand is a distortional hardening Mohr-Coulomb model described within a kinematic hardening, bounding surface framework. Strength is a variable quantity, dependent on the current value of state parameter which varies with shearing-induced dilatancy and changes in stress level. Particle crushing lowers the critical state line and hence tends to produce increase in state parameter and hence a looser response even without any change in volumetric packing. Dense material having crushed may liquefy and lose strength thus leading to increased run-out of debris flows.