Study On Deformation Failure Mechanism And Stability Of Tongziyuan Landslide In Xuanhan Coutry Sichuan Province

Tongziyuan landslide occurs in the typical low-deep sand shale interbed red beds. The gravity of low-deep red beds landslide can provide small sliding force, it is not enough to make the landslide formation. The formation of landslide is related to the peculiar nature of red beds and heavy rainfall. This kind of landslide is widely distributed in Sichuan Basin,poses a great threat to people’s life and property safety.Therefore,study on Tongziyuan landslide is helpful to reveal the deformation mechanism of red beds landslide,it is important to disaster prevention and mitigation.In this paper, take Tongziyuan landslide as the study object,on the base of collecting the data, field survey, field test and labrory test, application of geological theory and numerical simulation make comprehensive analysis to Tongziyuan landslide,the main research results are as follows:(1)Base on understanding the basic geological condition of the study area, elaborate on the scale, boundary, material composition, deformation and characteristics of Tongziyuan landslide. According to boundary, fracture distribution,deformation and failure characteristics of Tongziyuan landslide,the landslide is divided into four zones: tensile deformation zone;strong deformation zone;weak deformation area and overlap zone.(2)This paper analyzes the formation mechanism of Tongziyuan landslide accord to geological condition factor and rainfall factors,that the rainfall is the main factor for Tongziyuan landslide.The forming process of the Tongziyuan landslide can be divided into four stages: rainfall infiltration and fracture development;shear strength of weak layer reduce, uplift pressure generate;pore pressure and uplift pressure rise;slide. Restore the original landform of Tongziyuan landslide, using the discrete element software UDEC to simulate the deformation of the Tongziyuan landslide under different conditions. The results of simulation show that: Tongziyuan landslide slide under the condition of joint action of high pore pressure,uplift pressure and shear strength of weak layer reduce.(3)The stability of Tongziyuan landslide in the natural, rainstorm, earthquake, and earthquake+ rainstorm conditions were calculated by using the limit equilibrium method. Calculations show that: the landslide is stable in the natural condition.The stability of the landslide is reduced in earthquake condition. The stability of the landslide in rainstorm condition is lower than in earthquake condition.,the possibility of instability increases.The landslide slides in rainstorm+earthquake condition.(4) Using single factor analysis method to selcted cohesion, angle of internal friction, seismic acceleration to research the stability of Tongziyuan landslide.The most important factor to the stability of Tongziyuan landslide is angle of internal friction.(5) Using the finite element analysis software FLAC3 D to numerical calculation the stability of Tongziyuan landslide in the natural, rainstorm, earthquake, and earthquake+rainstorm conditions. The numerical analysis shows that: the characteristics of the natural condition show no signs of deformation and damage, landslide is in stable state. The maximum displacement of landslide is 5.2cm in rainstorm condition, local occur plastic continuous belt, shear stress increment through belt is not found,so the landslide is stable as a whole, local deformation may occur. The maximum displacement of landslide is 3.6cm in earthquake condition, The plastic deformation zone do not formation continuous belt, the slope has not formed shear stress increment continuous belt,so the landslide is stable.The landslide appears obvious deformation and failure in earthquake+rainstorm condition. The plastic deformation zone through the slope,shear stress increment continues bant occurs in the front of the landslide.(6) According to the deformation characteristic,influence factor,formation mechanism and stability of Tongziyuan landslide put forward“ pare the mass and relief weight + pull trap groove backfill +plugging cracks +drainage project ”to treatment Tongziyuan landslide.