DISCRETE ELEMENT ANALYSIS OF THE CAUSES AND FAILURE MODES OF THE EXTRA-LARGE RED ROCK LANDSLIDE

The occurrence of sliding on rocky slopes is not only related to their slope structure and tectonic development, but also to external dynamic factors. The M_S6.5 earthquake in Ludian, Yunnan Province in 2014 caused many large landslides and extra-large landslides. But, the Yunnan Jinggu M_S6.6 earthquake that occurred in the same year only caused only small and medium-sized landslides. In order to identify the main causes of extra-large caused by the Ludian earthquake, this paper takes the Red Rock extra-large landslide induced by the Ludian earthquake as an example. The particle flow PFC2D discrete element software was used to analyzing it, solves the problem of distortion of the tension-compression ratio by used two parallel cohesive models, soft and hard, and its cause and failure mode under the influence of various factors such as laminae, stress-release cracks, potential sliding surface, weathering cracks in the slope body, and earthquake are discussed. Based on the results of orthogonal tests and the development of slope cracks, the failure modes of seismically induced Red Rock landslides and the main factors affecting the scale of Red Rock landslides are discussed. The results show that the reason for the occurrence of an extra-scale landslides in Red Rock under the action of earthquake is the formation of deep sliding surface. The formation of deep sliding surface mainly comes from the influence of its own top-down ‘hard-soft-hard’ structure. The failure mode of the Red Rock landslide can be summarized as:Central soft rock and slope superficial damage-Hard rock overhang-Formation of shear bands-Large-scale landslide-Accumulation. The research in this paper has certain theoretical and engineering guidance significance for the prevention, assessment and management of seismically induced landslide hazards containing softly interbedded reverse-slip rock masses.