Shear fracture behavior and damage constitutive model of rock joints considering the effect of pre-peak cyclic loading

The research on mechanical properties and fracture nalysed of rock joints under dynamic loading disturbance is essential for the stability analysis of rock mass engineering. In this work, a series of pre-peak cyclic shear tests considering the number of cycles and cycle amplitude are conducted for rock joints. Firstly, the shear fracture nalysed and damage evolution law of rock joints are investigated in detail. Then, based on the statistical damage theory, the novel damage constitutive model of rock joints under pre-peak cyclic shear loading is established assuming that the microscopic element damage of rock joints material obeys the Weibull distribution. Finally, the real-time response of acoustic emission and the failure mode of joint surface are nalysed. The results demonstrate that the peak and residual shear stress are positively correlated with the cyclic amplitude. The cumulative cyclic displacement grows with the increase in the number of cycles and cycle amplitude. Moreover, the developed damage model considering the effect of pre-peak cyclic loading is verified by comparing the shear test results with the theoretical values, which are in good agreement. The variation of the shear wear zone of joint surface with cyclic parameters is discussed by binarization calculations. The results of this work can provide a valuable theoretical basis for further research on the shear fracture mechanism of rock joints under dynamic loading disturbance and mitigating geological disasters.