Cyclic shear responses of rough-walled rock joints subjected to dynamic normal loads
Qiang Zhu, Qian Yin, Zhigang Tao, Manchao He
Abstract
In rock engineering, the cyclic shear characteristics of rough joints under dynamic disturbances are still insufficiently studied. This study conducted cyclic shear experiments on rough joints under dynamic normal loads to assess the impact of shear frequency ( f h ) and shear displacement amplitude ( u d ) on the frictional properties of the joint. The results reveal that within a single shearing cycle, the normal displacement negatively correlates with the dynamic normal force. As the shear cycle number increases, the joint surface undergoes progressive wear, resulting in an exponential decrease in the peak normal displacement. In the cyclic shearing procedure, the forward peak values of shear force and friction coefficient display larger fluctuations at either lower or higher shear frequencies. However, under moderate shear frequency conditions, the changes in the shear strength of the joint surface are smaller, and the degree of degradation post-shearing is relatively limited. As the shear displacement amplitude increases, the range of normal deformation within the joint widens. Furthermore, after shearing, the corresponding joint roughness coefficient trend shows a gradual decrease with an increasing shear displacement amplitude, while varying with the shearing frequency in a pattern that initially rises and then falls, with a turning point at 0.05 Hz. The findings of this research contribute to a profound comprehension of the cyclic frictional properties of rock joints under dynamic disturbances. • Coupling effects of cyclic shearing and dynamic normal loads on nonlinear normal deformation of joints. • Assessing the role of sinusoidal shear frequency and amplitude on shear mechanical properties of joints. • Analyzing surface wear patterns and changes in the roughness of joints under cyclic shearing conditions.