Study On Formation Mechanism And Stability Analysis Of Loess-Mudstone Landslide

The Houhai landslide in Hao Shui Township,Lunde County,was taken as the object of study.The engineering geological characteristics of the landslide were identified through technical means such as site investigation,indoor tests,numerical simulation,and theoretical analysis.The causes of landslide formation were analyzed,revealing the landslide creep mechanism and damage mode.On this basis,the stability and future risk of the landslides were evaluated.The results are as follows:(1)Analyzing relevant literature and combining with regional geological data,the geographic environment,topography,stratigraphic lithology,geological formations,hydrogeological conditions,and human engineering activities of the landslide area were summarized and analyzed.(2)Through the landslide site investigation,the planform of the landslide,the lithology of the strata,the location and scale of the slide surface and its deformation and damage characteristics were identified,the physical and mechanical parameters of the landslide were tested and the formation conditions and causes of the landslide were assessed.(3)Triaxial creep tests were used to analyze the relationship between steady-state creep rate and bias stress and the variation of axial creep rate with time for slip zone soils under different confining pressures.The creep stress-strain curves of the slip zone soils were fitted,the long-term strength and parameters were determined,and an empirical creep constitutive model was developed and validated.(4)Using the finite element analysis software Midas GTS NX,a pseudo-3D model was obtained by extending a typical section of the Houhai landslide,and a true 3D geological model was established using the landslide plan and borehole data to simulate and analyze the stress-strain and deformation damage pattern of the landslide body under natural and rainfall conditions.Based on the engineering geological conditions of the landslide,the creep characteristics of the slip zone soil and the numerical simulation results,the landslide was determined to be a loess-mudstone contact landslide,and the damage mode was creep-slip-pulling type.The landslide formation and evolution can be divided into three stages:rainfall infiltration,softening of slip zone soil,creep cracking,and overall sliding.(5)The quantitative evaluation of landslide stability was carried out using the transfer coefficient method.Combined with the numerical simulation results,it was found that the landslide of Houhai Village Group 2 in Hao Shui Township,Lunde County,was in a stable state under natural conditions,while it was in an unstable state under rainfall conditions,and the landslide risk was predicted and assessed.