Study On The Mechanism And Treatment Measures Of Beltway Landslide In Leibo County

July 1,2017 at 5 am,landslide occurred in K4+900～K5+380 of Leibo County.The landslide damaged the road and nearby farmland and houses under construction.Through on-site sampling and analysis,combined with regional data,the development characteristics of the landslide are summarized.Use numerical simulation software to simulate the influence of external factors on it and analyze its formation mechanism.The results can provide a scientific basis for the field identification of this type of landslide and the summary of regional disaster laws.According to the characteristics of the landslide and the design specifications for prevention and treatment,a feasible treatment plan is determined,which can provide corresponding reference for the actual treatment project.The main research results are as follows:（1）The landslide as a whole is"inverted cone-shaped",with an oblique length of 710m,a width of 420m,a planar area of 2.2×105m²,and a total volume of 5.6×104m³.The terrain of the landslide is characterized by"slow-steep-slow".The initial main sliding direction is210^°,and then it is turned to 170^°due to terrain and retaining wall restrictions.According to the material composition and movement characteristics,the landslide can be divided into three parts:source area,movement area and accumulation area.（2）The landslide developed in the grayish yellow-brownish yellow basalt strata,the rock layer has a high degree of weathering,and there are three sets of dominant structural planes and a large number of micro-cracks in the rock mass,which provides the source conditions for the landslide.The sliding body in the source area maintains the original rock structure characteristics,the sliding bodies in the sports area and accumulation area are mainly gravel soil.In the early stage,due to the construction of the highway around the mountain,local deformation occurred on the upper part of the slope,and large-scale slippage occurred after entering the rainy season.（3）Determine the slope rock and soil parameters before the landslide by engineering analogy and inverse algorithm,and FLAC^3D is used to calculate the increment of shear stress and displacement of slope under different working conditions.The results show that after excavation,the stress on the slope is concentrated at the shear outlet,the displacement gradually increases,and the effect of stress concentration after rain is more significant.Comprehensive analysis believes that excavation and rainfall are the main inducing factors of this landslide.（4）According to the relevant design specifications and landslide characteristics,it is determined to take appropriate load reduction of the sliding body+anchor lattice near the shear exit+local slope protection+clearing of the overlying soil below the shear exit as the treatment plan.According to experience calculation,the stability after governance has reached the specification requirements.