Numerical study on the seismic fracturing and instability of anti-dip jointed rock slopes by the sub-block splitting DDA method

The seismic failure of jointed rock slopes is essentially a problem of dynamic fracturing and instability of discontinuous rock masses. In this study, seismic failures of anti-dip jointed rock slopes are numerically investigated by the sub-block splitting discontinuous deformation analysis (DDA) method. Firstly, diametrically compressive rock discs with a central pre-existing crack of different inclinations are simulated to verify the effectiveness of the sub-block splitting DDA method for rock fracturing simulations. Thereafter, the fracturing failure and instability process of five anti-dip jointed rock slopes with different configurations under the Wenchuan earthquake waves of different amplitudes are simulated. Results indicate that with larger excavation area of the slope and larger amplitude of the seismic loads, and under specific horizontal relative direction of the seismic wave to the slope (SSHRD), the slope stability will be dramatically reduced, and the failure mode will also be changed upon a basic mode of toppling. The surface and elevation amplification effects of the slope under seismic loads are successfully reproduced as well by the simulations. This work reveals the seismic failure process and mechanism of anti-dip jointed rock slopes, and could provide theoretical reference to the disaster prediction of anti-dip jointed rock slopes under earthquakes.