Abstract: JRC-JCS model provides a good idea for estimating the shear strength of joint surface, but it often overestimates the shear strength of jointed rock mass with poor consistency. The JRC-JMC model further considers the effect of joint matching degree on shear strength, which provides a good idea for estimating the shear strength of joint surface with poor joint matching degree. However, there are still difficulties in quantitative analysis of joint matching degree at present. Based on the analysis of the morphological characteristics of joint plane and the variation law of shear performance of joint surface, the quantitative calculation method of joint matching degree was proposed. The results show that: 1) Under the action of repeated shear, the shear strength of the jointed rock mass and the morphology parameters of the joint plane show a trend of decreasing first steeply and then slowly, and the matching degree between the upper and lower walls of joint surface decreases gradually. 2) According to the comparative analysis of joint surface topography before and after shear, the effective contact area of joint surface during shear process is determined, and the quantitative calculation method of joint matching coefficient JMC is proposed. 3) The comparative analysis shows that combining JRC and JMC can better reflect the influence of joint morphology characteristics on shear performance compared with the consideration of JRC alone. The related research methods and analysis results can provide a reference for the shear behavior analysis of joint surface.

Key words: jointed rock mass, shear strength, repeated shear, joint matching coefficient, joint roughness coefficient