Experimental study on the displacement evolution of rock interface friction slip based on crack

To study the further evolution characteristics of the fracture plane or structural plane after rock failure, the granite was chosen and prepared as double penetration crack samples, and the friction sliding tests were conducted using twin-shear model.During the tests, the CCD camera was used to record the speckle images, and the digital speckle method was used to analyze the evolution characteristics of horizontal displacement field, vertical displacement and horizontal displacement in the process of friction sliding.The results show that: ① The major role in displacement evolution has changed from confining pressure to a combination of confining pressure and shear stress at the stage of slow growth in shear stress.The displacement evolution is dominated by shear stress at the stage of linear growth in shear stress.The increase and decrease of interface occlusal degree and horizontal alternate displacement can be used as precursors of rock interface friction slip.② The appearance and disappearance of the flow around the horizontal displacement field are the precursors of the local and global slip of the specimen, respectively.③ The relationship between confining pressure and shear stress is characterized by the central contour inclination in the nephogram of displacement field, so it can also be used as precursors of partial and global slip of the specimen.