In order to investigate the influence of rock interface roughness on the mechanical characteristics of fault slip, the mechanical characteristics of rock assemblage structures with different roughness under different loading speeds and vertical loads in two-sided shear experiments are investigated. The results show that: the increase of rock interface roughness will improve the strength and arrangement level of the bumps, and the increase of the vertical load will increase the degree of the bumps closure, which will then affect the type and process of the rock slip. The increase of rock interface roughness will increase the interfacial cohesion and slip shear stress, and the average interfacial cohesion can be increased by 9.35% per unit of joint roughness coefficient (JRC) increase. Within a specific range of JRC, the microscopic force chain structure of the fault interface bumps is prone to fracture at the early stage of slip, which will lead to micro-impact precursor events. Increasing the horizontal loading rate reduces the fault surface shear stress during initiation of slip, but the reduction decreases with the increase of rock interface roughness, and the maximum difference of the reduction under different JRC reaches 4.26%.
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