Experimental investigation on the shear mechanical behavior and energy evolution of sandstone subjected to pre-peak cyclic loading

The shear mechanical behavior of rock under pre-peak cyclic shear loading is one of the key factors affecting the stability of slopes. A series of pre-peak cyclic shear tests considering the loading parameters including the number of cycles, frequency, and shear amplitude were carried out to explore the shear mechanical characteristics and energy evolution of sandstone. The results illustrated that the fatigue mechanics behavior of sandstone is highly influenced by cyclic amplitude and loading frequency. The peak shear strength is positively correlated with cyclic amplitude, while it decreases firstly and consequently increases as loading frequency rises. With the increase in cycles, the elastic and dissipated energy decrease rapidly at first and then stabilize, and the accumulated dissipated energy law is transformed from exponential to linear increase. Finally, real-time acoustic emission monitoring and digital image correlation were used to obtain the fatigue damage and crack evolution processes of rock.