| Meilishi 3# landslide is located in Foshan Township, Deqin County, Yunnan Province on the Lancang River left bank, it's about 4.1km from Gushui hydropower station to lanslide. At present, the landslide have obvious deformation and failure signs, the leading edge is collapsing step by step, the landslide have deformation in trailing edge, Once the landslide is unstable,it will affect the construction and operation of the Gushui hydropower station. Therefore, studying the mechanism and the revival mechanism of the landslide, and further evaluating the stability of the landslide will have project practical value of construction and operation, The research results have certain reference value for the stability evaluation of the similar slope in the reservoir area. The results of the study have value for the safety and operation of the Gushui hydropower station.Based on the detailed geological environment conditions and the engineering geological conditions of the landslide area, summarizes the basic characteristics of the landslide, in accordance with the analysis of mechanism in geological processes, using discrete element and finite element software to analysis of genetic mechanism and reactivation mechanism of landslide. Finally, using the limit equilibrium theory and the three-dimensional numerical simulation software to evaluate the stability of the landslide, the main research contents and results are as follows.(1)Meilishi 3# ancient landslide plane is "U" type, main sliding direction is NW43°, landslide distribution elevation is 2700 m ~ 3300 m, relative elevation of about 600 m, the distance between the Lancang river water surface and the front shear normal is about 650 m, the distance of the water storage position is about 430 m,it is a typical landslide, The average thickness of landslide accumulation is about 35 m, The landslide area is about 55 × 104m2, and the volume is about 1000 × 104m3.(2)Through detailed investigation of Meilishi 3# ancient landslide, the landslide have obvious deformation and failure signs, in various parts of the slope showed obvious signs of deformation front due to topographic factors, the leading edge is collapsing step by step, the landslide have deformation in trailing edge(3)The tectonic uplift of the landslide area is strong, and the Lancang River cutting quickly, the unloading of rock mass, rock have formation-bending deformation. Due to the thin layer of sandstone and slate, in the process of bending deformation, it is easy to be broken, and the fracture surface is formed. the continuous deformation of the slope will be controlled by the broken section of the slope,the deformation transfer to creep-cracking deformation.(4)Using discrete element software(UDEC) to study the slope deformation process in river downcutting, it is concluded that the steep layered rock bending-dump-break off the evolution process; using finite element software to study toppling rock evolution process of landslide, strong rock along the fracture occurs through the dumping of creep-crack.(5)Through the investigation and the data collection, the two factors which caused the rise of the landslide were identified. By means of numerical simulation study, reached the following understanding: rainfall process and accumulation in vivo shear strain concentration area, expanding the scope, value was increased at the same time, the packing of various parts of the body deformation gradually increases, and mainly concentrated in the front and middle; drains infiltration process of accumulation in vivo transient saturated zone range continues to expand, and lifting the underground water level, sliding zone close to saturation, resulting in infiltration after two years of stability coefficient is less than 1.(6)Using limit equilibrium system of global and local stability of the landslide is calculated, draws the following conclusion: landslide accumulation body under the natural state, the activity stability in good condition, but if considering storms, earthquakes in the extreme condition, after accumulation body stability coefficient decreased significantly, the existence of instability.(7)Using FLAC-3D software to analyze the stress and strain of landslide, draw the following conclusions: two kinds of conditions, the shear strain increment and the front were not through the landslide in two conditions are not large-scale slide; the heavy rain conditions, the displacement value increased significantly, the maximum displacement is increased from 13 cm to 30 cm, the landslide stability decreased significantly; The heavy rain conditions, the shear yield significantly expanded the scope of regional distribution, widely distributed in the front and around the landslide boundary, accumulation in front of the possible local shear failure. |
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