This study employed the Particle Flow Code in Three Dimensions (PFC3D) discrete element method to establish a synthetic rock slope model containing a single set of discontinuities to simulate collapse behaviors under
various oblique angle and rock slope conditions. Collapse energy was used as a quantitative index to determine the
effects of friction angle, slope angle, slope height, and discontinuity dip on the collapse energy and critical oblique angle. Simulations revealed that small oblique angles, moderate discontinuity dips, small friction angles, steep slopes, and great slope heights led to severe plane failure, resulting in both high collapse energy and a large critical oblique angle for stability. Under typical rock slope conditions, the critical oblique angle for plane failure was approximately 20°, although it may reach up to 40° in the presence of multiple unfavorable factors. In terms of toppling failure, large oblique angles, steep dips, steep slopes, and great slope heights resulted in high collapse energy and a relatively low critical oblique angle for instability. This study established continuous equations describing the collapse energy and critical oblique angle for plane failure and toppling failure. The results are highly consistent with PFC3D numerical simulations, which confirms their applicability to the evaluation of rock slope failure modes and collapse energy.
Key Words: Critical oblique angle, Dip slope, Plane failure, Toppling failure, Collapse energy