Experimental study on shear weakening mechanism of local roughness for rough rock fracture surface in different directions

The morphological characteristics of the fracture surface play a crucial role in determining its shear strength and deformation. Additionally, the fracture surface undergoes varying degrees of damage at different positions during the experimental process. This study aims to investigate the local damage mechanism of the fracture surface post-experiment, as it is essential for understanding the size effect and anisotropy of mechanical properties in rock masses. To achieve this, 3D scanning and 3D printing technologies were employed to create molds of rough fracture surfaces, and rock-like material mortar was used to cast samples of these rough fractures. The direct shear tests were successfully conducted on two rough rock fracture surfaces under varying normal pressures and shear directions. The analysis of the fracture surface's shear stress law indicates the presence of apparent anisotropy and varying damage modes in response to changes in normal pressure. Following the experiment, it was observed that the damage is localized on specific areas of the fracture surface, and its distribution characteristics are significantly influenced by the shear direction and normal pressure. Using 3D scanning technology, the JRC2D of various profiles and JRC3D of fracture surfaces are determined through the utilization of the geometric index WPA. Both local and overall roughness of the fracture surface were weakened after the shearing. Notably, the degree of local damage was found to be significantly related to the roughness feature at the corresponding position.