Study on Frictional Slip Behaviors of Rock Discontinuity Using an Impact-Induced Direct Shear Method

Understanding the frictional slip behavior of rock discontinuity is of great importance in earthquake engineering, geoengineering and disaster prevention engineering. Due to the inertia effect, the rapid stress change may cause some new slip characteristics of rock discontinuity subjected to dynamic loading. To address this issue, an experimental study on the frictional slip behaviors of rock discontinuity subjected to impact load is conducted. Shear tests on planar saw-cut granite discontinuities are carried out using an impact-induced direct shear method. A near semi-sinusoidal wave with a duration of about 330 μs is used as the dynamic shear load in the test. The slip displacement, velocity, acceleration and frictional resistance during the slip process are obtained. Then, the effects of impact energy on the aforementioned parameters are discussed. Test results show that the frictional slip of the rock discontinuity undergoes two main stages including accelerated slip and decelerated slip. As impact energy increases, the slip acceleration in the decelerated slip stage decreases, and the duration of the slip process increases markedly, even far beyond the duration of the dynamic shear load. It indicates that the inertia effect becomes increasingly important. Throughout the frictional slip process, the maximum slip displacement of the rock discontinuity is proportional to the impact energy. With increasing impact energy, the slip velocity increases, and the maximum frictional resistance of the discontinuity is negatively correlated with the impact energy.