Analysis of toppling failure mechanisms in anti-dip slopes based on FDEM simulation

• Strength reduction method is innovatively integrated with kinetic energy monitoring and failure surface detection to model the failure process of anti-dip slopes with an in-house parallelized FDEM. • The interplay between rock layers and structural planes in anti-dip slopes dominates the interaction and flexural failure of rock layers, which then trigger through-going slip surfaces and toppling failures. • 23 comprehensive modellings reveal how rock layer inclination, thickness and non-persistent cross-joints affect the stability of anti-dip slopes. An in-house combined finite-discrete element method (FDEM) is implemented to analyze the toppling failure process of anti-dip slopes. A strength reduction method integrated with kinetic energy monitoring and failure surface detection is applied to not only simulate the progressive slope failure process but also reveal complex failure mechanisms in anti-dip slopes. The FDEM is first validated through reproducing the through-going failure surface formation stage and the flexural toppling stage observed in laboratory experiments on anti-dip slope instabilities. Then, 23 numerical models are built to investigate the effects of slope geometry, thick layer position and cross-joint on the stability of anti-dip slopes. It is concluded that increasing slope angle leads to increasing failure surface depth and system kinetic energy but, decreasing factor of safety (FOS). Increasing rock layer inclination results in decreasing failure surface inclination but increasing failure surface depth. Increasing rock layer thickness, however, exerts limited effects on slope failure characteristics but enhances FOS. Furthermore, thick layer position has rather limited influence on FOS while cross-joints dominate the failure mode of anti-dip slopes. The numerical findings are expected to advance our understanding of complex failure mechanisms in anti-dip slopes and provide theoretical foundations for relevant slope stability assessment and prediction.