Analysis of Strength Characteristics for Granular Materials Based on Discrete Element Simulation

A series of numerical simulation of constant b cubic tests were conducted using discrete element method to study the strength characteristics of granular materials under different stress paths. The variation of peak stress ratio and development of fabric was studied. Contributions to strength of granular materials were analyzed based on the true stress concept and the development of fabric tensor. Numerical results indicate that the slope of peak strength line independent of stress path is only related to parameter b, and the peak stress ratio q/p decreases with an increasing b. Meanwhile, stress-induced fabric anisotropy is developed with the increasing strain. The strength of granular materials is the joint action of friction of particles and anisotropic fabric induced by the applied stress. Theoretically, the location of failure point in fabric ratio-stress ratio coordinate system is only decided by the particle apparent friction angle. The deviation between numerical simulation and theoretical analysis is origin from the effect of interlocking and rolling friction between particles and this influence is related to both particle friction coefficient and stress state.