Research On Formation Mechanism And Stability In The 4^th Landslide Of Ran-jiagou

This paper takes the 4th landslide of Ran jiagou in Yinchuan-Baise Expressway,which lies on the right side of Ranjia,as the research object.The landslide is a giant deep loess landslide.There are many multi-stage secondary cracks,transverse cracks and beaded caves on the landslide.Because the front slope of the landslide is washed by the water for the long time,there are many different scales of the slumping block.This landslide is a threat to the bridge and foundation of the proposed route,so it is important for the line selection of highway and the post-assessment of landslide control to analyze landslide's forming mechanism and accurate evaluation of its stability.Based on the background of the regional geological environment in Qingyang city of Gansu province,where the landslide is located,the paper analyzes the formation mechanism of landslide from forming conditions,forming reasons,the deformation process and the present situation of the landslide.And we analyze the stability of the landslide by using the limit equilibrium method.Slope instability is the external expression of the stress distribution in a landslide,we choose the numerical simulation,in order to have a further analysis of the stress distribution and deformation displacement.The paper mainly consists of the following parts:1.Based on the regional geological environment of Qingyang city,Gansu Province,including the regional geography,weather,hydrology,topography,and stratigraphic lithology,etc,the paper analyzes the forming conditions and inducing factors.2.Distortion and destruct of landslide generally divided into two phases.Original slope slided for the first time,which is the first stage.As the resistance sliding section of the soil was washed away and the effects of sliding resistance is subdued,landslide slide again,which is the second stage3.Limit equilibrium method is a traditional landslide stability evaluation method,which has mature theories and simple steps.For the 4th landslide of Ran jiagou,the paper calculates two kinds of condition of stability using the limit equilibrium method from four geologic profiles.In order to reflect the influence of various factors,we undertake a sensitivity analysis to the factors,which influence the stability of landslide.4.Based on traditionad limit equilibrium method,the paper uses the finite element numerical simulate software Midas/GTS to analyze the landslide's stress and distortion situation,which better reflect the landslide in process of deformation and failure.