Experimental investigation on interface dynamic friction of granite under combined pressure and shear impact loading

To investigate the dynamic friction behaviors of rock interface, series of experiments including oblique planar impact with inclination angle 20° and 30°, impact loading velocity ranging from 42.2 m/s to 130.6 m/s for Fangshan granite, are carried out. Experiments with inclination angle 20° were carried out to study interfacial properties for specimen without interfacial sliding, and those with inclination angle 30° were used to study the dynamic friction behaviors for specimens with interfacial sliding. Experimental results preliminarily revealed the dynamic friction behaviors of granite surface under the pressures range from 317 MPa to 685 MPa and the surface sliding velocities range from 2.76 m/s to 24.88 m/s. The preliminary results indicated a complicated process of the dynamic friction, which is helpful for the understanding of the earthquake slip.