Abstract: Based on the two-dimensional particle flow software (PFC2D), this paper studied the failure modes and dynamic response laws of rock slope with non-persistent joints by the combination of different dip angles of rock bridge and joint spacing under earthquake. The results showed that the bedding non-persistent jointed rock slope with single potential sliding surface present the sliding-block toppling mixed failure under the action of seismic dynamics. While the bedding non-persistent jointed rock slope with multi-potential sliding surfaces mainly present the block toppling failure. The dynamic stability of the slope was mainly controlled by the potential sliding surface composed of non-persistent joints and alternate connections of rock. Under the action of seismic dynamics, the wing crack at the rock section closest to the foot of the slope was first generated, resulting in the released tensile stress. Successively, each joint started to crack and expand, which eventually led to the step-like instability. Crack propagation was controlled by bedding non-persistent joints. Cracks are dominated by tensile cracks, and the number of cracks was synchronous with the acceleration of the input seismic waves. The existence of the joint surface had a significant impact on the dynamic response of the slope. The peak velocity and displacement along the slope surface and the horizontal direction increased with the increase of the inclination angle of the rock bridge and the decrease of the joint spacing. Meanwhile, the effects of joint spacing and rock bridge inclination on the PGA amplification factor were mainly on the slope surface and shoulder. Along the vertical direction, the peak displacement decreased with the inclination of the rock bridge and the joint spacing, and the curve of the PGA amplification factor exhibited U-shaped distribution with the elevation change.

Key words: rock slope, earthquake, dynamic response, rock bridge, non-persistent joint, PFC