Cyclic frictional response of rough rock joints under shear disturbances: Laboratory experiment and numerical simulation

The cyclic frictional response of rock joints under shear disturbances is critical for understanding the stability and durability of rock engineering structures. Laboratory experiments and numerical simulations were conducted to examine the effects of varying cyclic shear displacement amplitudes, frequencies, and cycle numbers on the macroscopic and microscopic shear characteristics of rough rock joints. The experimental results reveal significant differences in shear strength between the first few cycle and subsequent cycles during the cyclic shear process. As the number of shear cycles increases, the asperities on the contact surface gradually sustain damage, leading to a reduction in normal displacement. During cyclic shear, the peak shear load exhibits a two-stage variation with the number of cycles: an initial sharp decline followed by a gradual increase as the cycles proceed. The peak shear strength shows no obvious pattern under different shear displacement amplitudes and frequencies in the early stages of cyclic shear. As cyclic shear progresses, the peak shear strength decreases with increasing shear displacement amplitude but increases with higher shear frequency. Numerical simulations indicate that significant plastic deformation and shear wear occur on the joint surface during the initial cycles. The growth of the wear area is primarily concentrated in regions of stress concentration. Additionally, the simulations reveal that the volume of shear wear increase nonlinearly with the number of cycles. This research provides new insights into the cyclic shear behavior of rough rock joints and offers valuable references for engineering applications.