Evolution of joint morphology subjected to shear loads based on Gaussian filtering method

Two kinds of rock joint samples underwent a monotonic shear test under three different normal stresses. Three-dimensional laser topography instrument Talysurf CLI 2000 was used to acquire 3D joint surface morphology. Based on Gaussian filtering method, the original joint surfaces were divided into waviness surface and roughness surface, which can be analyzed separately. Then, the morphological evolution of joint surface subjected to shear loads was investigated by analyzing joint specific roughness coefficient (S) and joint surface degradation degree (Ds) quantitatively. The experimental results show that the entire roughness of waviness surface and roughness surface has a clear decline due to the damage of asperities during the shearing process. The degradation degree for waviness surface increases gradually with the increase of normal stress, while the maximum degradation degree for roughness surface appeares after the first shear test and it is greater than the degradation degree for waviness surface. The morphological evolution of original joint surface is mainly dominated by roughness surface and waviness surface, respectively, under low and high normal stresses.