Shear behaviours and roughness degeneration based on a quantified rock joint surface description

Abstract

The asperity wear of rock joints significantly affects their shear behaviour. This study discusses the wear damage of the asperities on the joint surface, highlighting the roughness degradation characteristics during the shear process. The direct shear experiment of artificial specimens containing rock joints was conducted under different normal stresses based on three-dimensional scanning technology. These experimental results showed the contribution of joint wear to roughness degeneration, such as the height, zone, and volume of asperity degeneration. The wear coefficient of the rock joint was obtained based on the volume wear of asperities in the laboratory experiment. The functional relationship between the friction coefficient and wear coefficient is subsequently determined. To quantitatively analyse the wear damage of a joint surface, a calculation method for determining the wear depth of the rock joint after shearing was proposed based on wear theory. The relationship between the ultimate dilation and wear depth was analysed. A coefficient m, which can describe the damage degree of the joint surface, and a prediction method of joint surface roughness after shearing are established. Good agreement between analytical predictions and measured values demonstrates the capability of the developed model. Lastly, the sensitivity factors on the wear depth are explored.