Experimental and Numerical Study on the Damage Evolution of Random Rock Joint Surface During Direct Shear Under CNL Condition

Abstract

Because of the complex structure of joint surface morphology, the damage evolution of joint surface during direct shear was hardly investigated. In this paper, a series of direct shear tests were conducted on broken joint obtained by breaking rock cubes under constant normal loads condition. The surface morphologies of rock joints were tested by laser scanning technique and damage evolution and damage area of joint surface during direct shear were studied by means of numerical simulation. The damage quantities of rock joint during shear were defined as the volume of broken elements. Results of numerical modeling and laboratory tests show that, most damage of joint surface happens in the pre-peak stage and post-peak stage, and the damage area of joint surface enlarges greatly in post-peak stage. Damage evolution rate decreases with the shear stress in the residual stage and kept a rather low rate until the end of direct shear. The failure modes of convexes include two cases: friction failure in the top of peaks and shear broken in the root of peaks.