Deformation Mechanism And Treatment Measures For Lengjiashan Landslide In Yingjing Area Of Sichuan

According to the geological structure characteristics and the structure composition of the sliding body of Lengjiashan landslide in Ya'an,the basic characteristics of the landslide,such as the geological environment conditions,the structure,distribution,scale of the landslide disaster body,the thickness of the landslide body and the geotechnical engineering characteristics,were ascertained.The stress distribution,deformation development and stability coefficient evolution of #H1 and #H2 landslides were analyzed by using finite element method.The stability,hazard and development trend of landslides were evaluated,which provides the basis for stress and deformation control in the prevention and control area of Lengjiashan landslide disaster and the design of control project.The main research results are as follows:(1)The inner surface of the front edge of Lengjiashan #H2 landslide is warped and cracked,and the whole slope is in front of the creep deformation,resulting in swelling and deformation of the front slope.The #H1 and #H3 landslides are traction landslides caused by shear failure of sliding surface soil,which are small landslides.(2)The calculation theory of transfer coefficient shows that cohesion and internal friction angle are two related parameters.For a limit equilibrium equation of a single section,the results obtained by the inversion test method are not unique,so the parameters of the geological sections which are both in the limit state at the same landslide interception should be inverted and analyzed separately.When the parameters are retrieved,the cohesion value can be determined first,and the friction angle values of the parameters are calculated according to the inversion model.In the evaluation of landslide stability and the design of Engineering treatment,the parameters of rock and soil strength should be retrieved and compared with the results of laboratory tests,and the values should be reasonably selected.(3)The shape distribution of bedrock affects the stress distribution,deformation development and stability of the landslide.The stress distribution of the Lengjiashan landslide with steep-long composite interface is related to the shape of the bedrock surface.The part of the landslide above the convex position in the middle may have tensile stress.The possibility of landslide sliding is greater,and the possibility of secondary sliding is smaller.(4)The location and distribution of potential slip surfaces are different,and the stability of #H2 landslide is different.It is unstable to unstable state under thecondition of heavy rain and unstable state under the condition of normal groundwater level.The monitoring results of control measures of Lengjiashan landslide project show that the accumulative horizontal displacement of A-type anti-slide pile is 7-12 mm and the accumulative vertical displacement is 7-14 mm,and the displacement and deformation of each point are within a reasonable range to achieve the effect of landslide deformation control.