Study On The Mechanical Parameters And Stability Of The Accumulation Located In The Left Bank Of The Shaping â…¡ Hydropower Station Dam In The Dadu River

China is a country prone to geological disasters, mostly are the superficial department disasters such as collapse, landslide, debris flow, etc, particularly in the southwest region. According to statistics from Chinese Academy of Sciences, debris flows and landslides caused economic losses of 2.5 billion to 4 billion, and which killed 500 to 1,000 people each year over the past 10 years. With the rapid population growth and over-exploitation of land resources, slope problem which parallels with the earthquake and volcano has become one of the three global major geological disasters. It's a serious threat to the safety of state property and people.The accumulation, in this article, located in the left bank of the ShapingⅡHydropower Station dam in the Dadu River. The dam is about 230m from the Guanliaohe estuary, concrete dam, which top elevation is 557m and the length is 320.2m, the maximum height is 63.0m. The normal water level of the hydropower station is 554m, reservoir storage capacity is 2084 million m~3, total capacity is 345MW. The accumulation body flared along the SWW direction, like a trumpet. Front elevation was about 545m, closing to the Dadu River; posterior margin elevation was about 790m, the junction of steep slope relief. Its elevation from front to posterior margin was about 245m, vertical length of about 375m, horizontal length of about 390m, the distribution area of about 10.6×10~4m~2, the average thickness of about 20m, the volume of about 200×10~4m~3. Such a large accumulation body just located in the left bank of dam, so the choice of dam location and the security operation of hydropower station are seriously affected by its stability. Once collapsing, it will directly endanger the dam and other important construction safety. So that it is necessary to research its mechanical parameters, and go further to analyze its stability in depth and detailedly. In order to accurately judge the stability of the accumulated body, based on the research of geological environment, establish conceptual model of geological mechanics. According to basic features, pattern of deformation and failure, formation mechanism and influence factors analysis, focus on researching the mechanical parameters of rock and soil covering on the slope. The research selects four methods such as laboratory experiments, empirical formula, engineering analogy and inverse calculation. To laboratory experiments, it includes large shear experiments, true triaxial experiments and direct shear experiments. The research shows that the large shear experiments statistical results are a little higher than another two experiments, however all of the experiments statistical results are almost closer as a whole. At the same time, the experiments results are within the scope of engineering analogy statistical results, which are slightly higher than empirical formula results and inverse calculation results. By comprehensive comparison and statistical analysis of several methods results, determining the calculation parameters of the accumulation body finally.Based on the research of accumulation mechanical parameters, going further to forecast its overall and local stability by numerical simulation and limit equilibrium calculation. Based on the research of accumulation mechanical parameters, go further to forecast its overall and local stability by numerical simulation and limit equilibrium calculation. The overall stability is calculated in nature,heavy rain,earthquake and excavation condition. Also search and compute its potential unstable block. Then use FLAC sofeware to simulate and analyze its stress,deformation and stability feature. The research shows that the accumulation body is stable in nature, basic stable in heavy rain, limit equilibrium～instability in earthquake. Because of excavation, the volume of unstable body in front is more than which is in the middle. There is not existing unstable body in the posterior edge. To contrast before excavation, the horizontal displacement increased clearly in part of body foot on the excavation face, the increased concentrating strip of shear strain extended further. So that it is easy to collapse along excavation face.Finally based on the form of damage and scale of destruction of the accumulation body, go further to analyze the engineering effect while collapsing. The research shows that there does not exit danger by climbing over the dam because of a lower surge height which caused by unstable body in front. And it also influences faintly to reservoir storage capacity by a lower volume of alluvial object.