Flexural toppling is one of the failure modes of anti-dip rocks, is often triggered by seismic load, occurs haphazardly under an earthquake scenario, and is characterized by high speed and extreme energy, leading to catastrophic disaster consequences and huge losses. However, there is limited literature that reveals its failure mechanisms and describes the failure surface due to earthquakes. Therefore, based on the limit equilibrium analysis method, the horizontal pseudo-static load was applied to improve the geological mechanical model under gravity only, and the stability analysis process was derived. The failure surface and failure mode of the slope under different seismic loads were analyzed. The results indicated that, with the increasing seismic load, an increase in the number of rock layers with sliding failure increased the number of rock layers with cantilever toppling failure; in contrast, the number of rock layers with overlapping toppling failure decreased. The slope toe was more prone to sliding and the slope top was more prone to cantilever toppling under an earthquake, which decreased the stability of the anti-dip rock slope.

Based on the discrete element numerical simulation, the change rules of safety factor and failure modes of slope influenced by parameters of rock mass structural plane is studied. Based on the principle of variance analysis of orthogonal experiment, significance of the rock structural plane parameters to the stability of slope is studied. It is shown that slope safety factor is linear increase in a certain range with the increase of the strength of the rock mass structural plane, and the failure modes shift gradually from the bedding sliding failure modes to the sliding-bending failure modes. Extent of variation of safety factors changes very little with the increasing of the normal and shear stiffness and spacing of rock structural plane, and the slope failure modes are mainly sliding failure modes. Slope safety factor firstly decreases and then increases and finally decreases with the increase of the rock structural plane dip angle, and failure modes shift from shearing slip failure modes to shearing slip and buckling failure modes and finally to the tilting failure modes. The impact of the rock structural plane cohesion to the slope stability is the greatest, and the stiffness is the least.