Simulation analysis of landslide disaster movement process in Xigeda Formation, Luding County, Sichuan Province

The Xigeda Formation developing in Luding County, Sichuan Province, is mainly composed of semi-diagenetic rocks, which has complex engineering geology properties.Shallow creep deformation of the Xigeda Formation often occurs in the slope with high and steep terrain.It can transform into debris flow after destabilization under the action of heavy rainfall.In this paper, the Huanhuancun landslide in Haiziping developing in the Xigeda Formation was selected as a study case.Based on remote sensing interpretation, field investigation and numerical simulations, we analyzed and calculated the development characteristics of landslides, potential instability modes and the process of landslide-debris flow movement.This study has shown that the Huanhuancun landslide is mainly developed in the Xigeda Formation, mainly in the shallow deformation with a depth of 3~5 m, and is in the creep deformation stage as a whole.The landslide in plane can be divided into strong deformation zone(A) and weak deformation zone(B) with the volume of approximately 5.5×10⁴m³ and 5.8×10⁴m³.Under different rainfall conditions, there are only two forming patterns of disasters: zone A sliding and zone A pulling zone B sliding together and transforming into gully debris flow.When only the zone A slides downslope, the longest movement distance can reach 1325 m, the maximum thickness of deposits is 5.2 m, the maximum velocity is 41.6 m/s, and the sliding body will damage the residential areas and roads.When the zone A and B slides together, the maximum movement distance can reach 1345 m, the maximum thickness of deposits is 7.7 m, the maximum velocity is 44.3 m/s, and the sliding body can rush as far as the other side of the river, forming a landslide dam with a height of about 3 m.The research results have certain guiding significance for deepening the understanding of remote disaster effect of shallow landslide-debris flow and disaster prevention and mitigation.