FLAC/PFC2D HYBRID SIMULATION FOR SEISMICALLY INDUCED FAILURE PROCESS OF TOPPLING ROCK SLOPE

This paper presents FLAC/PFC2D hybrid numerical models for a typical toppling rock slope with intermittent bedding planes and orthogonal secondary rock joints inside. The seismically induced failure processes of the slope are simulated and analysed. The simulation results reveal that the rock bedding plane generally fails in shear during the dynamic failure process. Very few tensile failure of the bedding plane can occur on the top of the slope. But the tensile failure always appears after the collapse of the whole slope. Therefore the tensile strength of the beddings cannot serve to affect the actual dynamic stability of the slope in a whole. Secondary rock joints on the top of slope can only fail in tension, resulting rock layer toppling. The joints on the bottom of the slope can fail both in tension and shear, inducing shearing displacement along the penetrating joint surfaces. Moreover, the joint failure at the top of slope always occurs before the joint failure at the bottom, which is completely opposite to the classic failure sequence of toppling rock slope on static condition. This difference may be due to the dynamic amplification effect on the crest of slope and the difference on position and depth for failing secondary rock joints on the top and on the bottom.