Quantifying landslide risk at a shale-debris interface using probabilistic and discrete element methods (Case study: the Khor Khor Pass, Iran)

This study used probabilistic methods and the distinct element method (DEM) to analyze the Khor Khor landslide, considering the slope's geological and engineering properties. Monte Carlo simulations were conducted to assess slope stability, revealing a staggering 100% failure probability at the most critical surface, corresponding to a safety factor of 0.80. Sensitivity analysis identified the internal friction angle of the debris layer as the primary factor influencing failure probability. The presence of water within the debris layer, overlying impermeable shale layers, further reduces the safety factor to 0.60. Stability analysis revealed the formation of distinct failure surfaces at the debris-shale interface, with significant displacements occurring along this boundary. The presence of serpentine minerals within the debris layer, known for their lubricating properties, contributed to these displacements. The DEM models accurately predicted the slope's behavior, particularly in terms of identifying the most critical section of the landslide. This finding offers valuable insights into the failure of relatively low-angle slopes (less than 20 degrees) in the region.