| Sanjia village is located at the junction of quzika township and yanjing township in mangkang county,qamdo city,Tibet autonomous region.The proposed quzika hydropower station is the first hydropower station in the cascade development plan from ancient water to miaowei river in the upper reaches of lancang river.There are active faults in the upper reaches of lancang river and three villages and villages in the lower reaches of lancang river.Limited by the faults and villages,the selection of dam site cannot effectively avoid the collapse and accumulation of sanjia village.Once the accumulation body is unstable,it will have a great impact on the construction of the whole hydropower station and the safety of people’s life and property.The genetic mechanism of sanjia village collapse accumulation body remains to be studied,and its stability is not clear,so it is of great theoretical significance and practical value to study the genetic mechanism of sanjia village collapse accumulation body and analyze its stability.On the basis of summarizing regional geological conditions,through studying engineering data such as drilling hole and adit,combining with geotechnical mechanical test and SIGMA software analysis,the formation conditions and genetic mechanism of sanjiacuns collapse accumulation body are summarized.Geo-slope software and FlAC3 D software were used to carry out numerical simulation and study the stability of avalanche accumulation body in combination with engineering geological conditions.The following results were achieved:(1)The formation of collapse and accumulation of sanjia village on steep bank slope provides inducement.The formation of collapse and accumulation body of sanjia village is caused by various formation conditions such as geomorphology,formation lithology,geological structure,rock weathering,rock unloading,rock alteration,rainfall and so on,combined with the cutting action of river valley,which leads to the formation of collapse and accumulation body of sanjia village.(2)Based on the engineering geological characteristics of sanjiacun landslide accumulation body,combined with the rock and soil physical and mechanical properties of the accumulation body,the finite element software was used to construct the model of valley cutting in the accumulation body region,and study the mechanical mechanism of the accumulation body evolution process.Due to the rapid cutting of lancang river,the stress field of the bank slope changes significantly.The evolution of sanjia village’s accumulation,collapse,slip and accumulation is divided into three stages for analysis,and the formation process of sanjia village’s collapse and accumulation is objectively shown.(3)Based on the GEO-STUDIO software,the use of quantitative methods to deposit under natural condition,storm conditions and earthquake conditions of overall and geotechnical interface stability was calculated,and analyzed the determined by the spatial structure may be deformation failure mode: along the base-cladding interface integral sliding mode and layered two specified sliding surface and sliding mode.The results of calculation and analysis show that the stability coefficient of the accumulation body under three working conditions is within the allowable range,and the safety reserve is high.(4)Based on FlAC3D software,the stability of sanjiacun landslide accumulation body under natural working conditions,rainstorm working conditions and earthquake working conditions was simulated and verified,and stability analysis was carried out from the aspects of shear strain increment,displacement field law and stress field.The results show that the maximum values of shear strain increment and displacement are mainly in the surface layer of the middle and lower edge of the accumulation body and near the foot of slope.The stability coefficient is lower than other strata of the accumulation body,but the accumulation body is relatively stable as a whole. |
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