Stability Prediction And Instability Criterion Of Typical Accumulation Landslide In Minxian County,Gansu Province

The formation or resurrection mechanism of landslide is the basis of landslide disaster prevention,and the instability mode of landslide is the basis of landslide disaster prevention.Minxian County of Gansu Province is one of the areas with high occurrence of geological hazards.Landslides are the main geological hazards in the area,among which the large landslides are mainly accumulation layer landslides.In this paper,Machang landslide and Wendou landslide,two typical accumulation layer landslides in Meichuan Town,Minxian County,were selected as the research objects.Based on field investigation and monitoring,SEEP/W+SLOPE coupling and SEEP/W+FLAC3D coupling numerical simulation were used to study the landslide rejuvenation mechanism and activity trend.The results showed that:(1)Under natural working conditions,the overall stability coefficient of Machang landslide is 1.11,and the whole landslide is in a stable state.The local most dangerous slide is located in the front of the slope body,and its stability coefficient is 1.03,and it is in an understable state.The overall stability coefficient of Wendou landslide is 1.33,and the whole is in a stable state.The most dangerous part is located in the front part of the slope,and its stability coefficient is 1.07,and it is in a stable state.(2)Under the rainfall condition,the rainfall of the front part of Machang landslide is72mm/24 h when the slope is partially unstable;the critical rainfall of the whole landslide is108mm/36 h when the slope is partially unstable;the rainfall of the front part of Wendou landslide is 90mm/30 h when the slope is partially unstable;and the critical rainfall of the whole landslide is216mm/72 h when the whole landslide is partially unstable.(3)Under the earthquake condition,the overall stability coefficient of Machang landslide is0.994,entering the unstable state.The overall stability coefficient of Wendou landslide is 1.25,and the whole is still in the stable state.The most dangerous part is located in the front of the slope,and the stability coefficient is 1.05,and the slope is in the stable state.(4)the racecourse and bucket landslide under critical rainfall conditions were towed instability mode for block classification,slope slope with the increase of the weight of full water,and to the reduction of effective stress in geotechnical engineering is the front of landslide,first of all,the inner mechanism of the instability,and the rear part of the slope after losing the front support of soil,of lateral unloading,until the whole slope instability along the sliding zone-bedrock interface.(5)Machang landslide presents a sliding overall instability mode under seismic conditions.The instability mechanism of Machang landslide is that the seismic stress facing the slope pushes the slope body to slip along the weak slip zone-bedrock interface.