| Taking the landslide in the south of Lanping county as the research object in this paper. Using testing methods such as data collection, geological survey, laboratory analysis to analyze the causes and mechanisms of deformation and failure of landslides. With numerical simulation methods, the paper analyzes slope stability, the following conclusions can be drawn:(1) After field investigation, we found that the landslide area is located in the slope areas in the west bank of Bijiang river. The body of slope is composed of the loose soil, the weak and semi-concreted of clay shale and argillaceous siltstone. The structural surface of rock mass is out-dip structural plane. Groundwater types are Semi-solid rock fracture water and Loose pore water.(2) By analyzing the geological environment conditions and the slope deformation characteristics of the landslide area, we found that there is a deviation of the division of landslide during the preliminary survey. In this study, we put the buried fault (F9) as the boundary, divide the landslide area into northern and southern landslides (Namely Ⅰ, Ⅱ landslides). After management, the No.1landslide in northern is basically stable, but the management effect of No.2landslide in southern is not very well, it is still sliding to eastward.(3) The microscopic thin section identification results indicate that the mineral composition of the mud shale rock which outcropping in Lan-ping landslide area are arranged orientation, and mineral composition is given priority to with clay minerals; Argillaceous siltstone cemented type is the base cemented, particles are mainly quartz, filled with clay minerals. X-ray diffraction results show that the mud shale and argillaceous siltstone rock mass are rich in Magnesium ion, Calcium ion, Carbonate ions and Carbon, these elements and compounds are prone to react physical and chemical reactions in the water.(4) With the water-rock disintegration test and the physical and mechanical properties measurement show that the weak and semi-concreted of clay shale and argillaceous siltstone are easily destroyed in the water, its mineral composition and physical and mechanical index changes strongly in water-rock interaction. The natural soil liquidity index is between0.11and0.83, plastic or soft plastic, some local weak weathered rock and soil is hard plastic; the weight of rock and soil in saturation increased by0.65to4.93percent than the natural state; the shear strength index of rock and soil is decreasing by22to55percent.(5) By analyzing deformation and failure characteristics and formation mechanism of the landslide, earthquake functions have a small influence on the landslide area in South of Lanping county. The cause of landslide is mainly controlled by the conditions of lithologic structure and bad geological process; Rainfall and human engineering activities are the main external inducing factors to landslides. Under the condition of rainfall, the action of seepage by surface water leads to physical and mechanical properties of rock and soil mass decline sharply, the softening of rock mass deformation formed perforating weak structure plane, these provide a good lithological associationconditions and water conditions for the formation of slip soil, the deformation and failure has an obvious character of peristaltic and slidable.(6)This paper built a three-dimensional model for calculating the slope stability. Using the shear strength reduction method which based on FLAC3D, based on a special point of displacement mutation to calculate the Slope stability coefficients and the deformation displacement of monitoring point under different intensities conditions. Combining with the deformation characteristics of landslide, we consider the destroy mechanisms of landslide is creep and crack.(7) Comparison and analysis of existing prevention engineering and management effectiveness,put forward the anti-slide piles as the major control measures, with the Corresponding drainage measures as a supplementary measure at surface and underground. |
PDF Full Text Request