Prediction And Analysis On Revival Conditions Of Loess-mudstone Interface Landslides In Longlin-Yanguan Section Of Longnan

The loess-mudstone interface landslides are widely distributed in the area under the jurisdiction of Yanguan Town to Longlin Town,Longnan City.The surface of this type of landslide is covered with the Upper Pleistocene Malan loess(Q₃^eol),and the underlying Neogene(N^a)mudstone,which presents a typical"double-layer heterogeneous"structure with poor stability and easy resurrection.The research on the resurrection conditions of this type of landslide can directly provide theoretical basis for the early warning,prevention and disaster risk management of local landslide geological disasters,and also provide certain reference for the prevention and control of similar landslides in other areas.Therefore,this paper selects the“Nanshan landslide”in Dongtai Village,Chengguan Town,Li County as the research object,and uses the SEEP/W and SLOPE/W modules in Geo Studio to perform coupling analysis and calculation to analyze the resurrection conditions under three conditions:rainfall,earthquake,and rainfall+earthquake.,And use GTS/NX software to carry out the numerical analysis of stability,stress,strain and displacement,and discuss the resurrection deformation and failure mode of Nanshan landslide.Mainly gained the following knowledge:(1)The influence of rainfall on the stability of landslides at the loess-mudstone interface is closely related to rainfall intensity and rainfall duration.The general rule is that the lower the rain intensity,the longer the landslide will be revived,while the greater the rain intensity,the landslide will lose stability.The rain for the resurrection will be shorter.(2)The stability of the Nanshan landslide is obviously affected by the earthquake.The greater the seismic acceleration,the easier it is for the landslide to lose stability and resurrect.(3)When rainfall and earthquake conditions are considered at the same time,the rainfall duration for landslide instability is greatly shortened,showing that the greater the rain intensity at the same seismic acceleration,the shorter the rainfall duration for landslide instability and resurrection,and the lower the rain intensity,the landslide instability The resurrection rain lasts longer.(4)The deformation and failure mode of the Nanshan landslide induced by the earthquake is that under the action of inertial force,the trailing edge of the steep slope body produces tensile cracks,which slide down along the loess-mudstone contact surface to push forward the old landslide;Creeping deformation-trailing edge pull crack-pull crack penetration-old sliding body slippage-front edge bulge.