Study On Strength Characterics And Stability Of Sliding-zone Soil Of Jinpingzi Creep Landslide

Jinpingzi landslide is located on the right bank of Jinsha River.It is about 900 m from the dam site of Wudongde Hydropower Station,showing an obvious concave slope with a total volume of 625 million m³.Jinpingzi landslide is divided into five areas.This paper mainly studies the creep landslide in area II.The strength characteristics of sliding-zone soil are closely related to the stability deformation and failure behavior of landslides,and the study on the influencing factors of strength can solve the problem of deformation and instability of landslides.Therefore,this paper takes the sliding-zone soil of Jinpingzi landslide area II as the research object,uses direct shear/residual shear apparatus and ring shear apparatus to study the shear strength of sliding-zone soil with different influence factors,and uses numerical simulation sofeware to calculate and analyze the main factors affecting the sliding of landslide.The main conclusions and achievements of this paper are as follows:?1?The influence of different clay contents on the characteristic strength of sliding-zone soil was studied by using a redirect shear test device.The results show that the shear strength of sliding-zone soil samples decrease nonlinearly with the increase of clay content,but the decrease amplitude increases with the increase of positive pressure;there is a linear negative correlation between peak internal friction angle,residual internal friction angle and clay content within a certain range,while peak cohesion and residual cohesion fluctuate with the increase of clay content.However,there was a certain decrease at 40%.?2?The relationship between shear strength and slip rate of sliping-zone soil was studied by ring shear.It is found that with the increase of shear rate,the peak strength of samples increases,but its effect on residual strength is almost zero.?3?In order to study the recovery of the shear strength of the samles,the shear rate was changed to continue shearing on the basis of shearing to a stable residual state.The results show that the residual strength decreases with the increase of shear rate,but the peak strength increases to a certain extent compared with the residual strength at the first shear rate,but all decrease again after a small shear displacement.?4?The change of strength parameters of sliding-zone soil will change the thrust of landslide body,the stability of landslide under different working conditions are simulated by FLAC^3D.Through the simulation of landslide stability under different working conditions,it is concluded that the most sensitive factor affecting the stability of area II is the internal friction angle of sliding-zone soil,followed by the groundwater level of sliding body,and finally the cohesion of sliding-zone soil.It is suggested that the control and protection measures of interception and drainage should be taken in area II of Jinpingzi landslide.