Study On Deformation And Failure Mechanism And Motion Process Of Liujian Landslide

The mountainous area of southern Shaanxi Province is one of the areas prone to landslide geological disasters because of its complex geological conditions,prominent topography,developed faults,broken rock mass and abundant precipitation.In this paper,taking the accumulation layer landslide-Liujian landslide induced by typical rainfall in Luonan County,Shaanxi Province as an example,based on field investigation,taking surveying and mapping,exploration and indoor routine geotechnical test as the means,combined with the geological environment conditions of the landslide.Based on the transfer coefficient method of limit equilibrium theory,the stability of landslide is evaluated under natural and rainfall conditions.The dynamic evolution process of occurrence,development and failure of landslide is simulated by PFC2D program.The deformation and failure mechanism of landslide is analyzed by setting a measuring circle at the key position,monitoring the change of stress and porosity,and analyzing the mechanism of deformation and failure.The displacement and velocity changes are monitored by tracing the characteristic particles,and the motion characteristics are elucidated.The rationality of the motion characteristics is discussed by comparing the numerical results with the theoretical results.The main conclusions are as follows:(1)Under the condition of heavy rainfall,the slope weight increases,the shear strength decreases,and the slope body is in the unstable state of creep sliding.(2)The landslide has the mechanical properties and characteristics of the joint action of the rearward displacement and the frontal traction.It is demonstrated that the landslide deformation occurs first in the foot of the slope and in the upper part of the slope body,and is continuously towed from the bottom to the upper part of the slope,and the upper part of the slope body is upward.The next step,expansion,Finally,it leads to the failure of the whole landslide.The overall characteristics are upper movement,middle shear,and lower traction.(1)The main slide stage of the landslide lasts for 25 s,the maximum speed of the main landslide is 13.4 m/s,the local maximum velocity is 19 m/s,the displacement of the center of mass of the landslide is about 170 m,and the local maximum displacement is 180 m.The general trend is that the higher the initial height,the greater the maximum velocity and displacement of the local slope body.