| Gendakan landslide is located on the the Lancang River belongs to Deqin county of Yunnan province, the geographical coordinates is latitude 28°36’25" and Longitude 98°44’47". It is the first stage of the hydropowe development planning cascader on the upstream of Lancang river in Yunnan province. Gendakan landslide is located on the right bank of Lancang river which between the upper dam and lower dam, the distance between the upper dam and landslide site is about 4km, the distance from the lower dam to the landslide site is about 3km. Landslide unstable failure will directly affect the safety of the building nearby the hub, and it will cause reservoir sedimentation problems or even make the landslide become a second dam. Which will resulting in the tail water elevation and cause a great threat to the reservoir and hub construction. The landslide may cause surge, which may take a great impact on the safety of the reservoir buildings. This paper elaborates on engineering geological conditions of the Gendakan landslide dam hydropower midstream, combined with specific engineering practice in the field. Drilling data and basic information on the adit from landslides morphology, composition of matter the basic features characteristic aspects, features and slider bed rock deformation and failure characteristics are summarized in the landslide; through field survey data and preliminary results, the mechanism of their formation and evolution analysis to determine and verify its genetic mechanism. The landslide is a valley high rock slope unloading dump formed through surface under dynamic geological seismic substandard induce the formation of rain, then after the formation of post-traceable transformation took place many times during creep to form a multi-level terraces landslide, now reach the bottom boundary of the valley, and the river here forms a prominent curved northeastward, currently part of imbricated slip. Through the Gendakan landslide mechanism analysis to determine the geological model and the failure mode, using qualitative and quantitative calculation method for determining the current stability of the landslide and possible damage trends analysis and evaluation, which reduce landslides generated damage and loss is very significant.In this paper, qualitative geological judgment method and limit equilibrium finite difference method are used. The stability of the overall landslide and the reservoir after impoundment are systematic analyzed, calculated and evaluated. First, limit equilibrium analysis software Geo-studio preliminary calculations landslide stability coefficient under various conditions, then use the three-dimensional geological modeling software FLAC-3D to make three-dimensional numerical simulation. At the same time, the stress field characteristics and deformation features of the landslide are analyzed, and the simulation results and the conclusions are compared to the results of the limit equilibrium method. Finally, check the suitability of mutual advantages and disadvantages of these several methods and compare these two methods. Through the analysis and research of the landslide destruction and damage scale,Provide the basis for the landslide hazard assessment and develop appropriate protective measures. The results showed that, as a whole, the Genduokan landslide of natural state is in the limit equilibrium state; under heavy rain, earthquakes and reservoir storage state, the overall stability of landslide will decreases and make the landslide in unstable state. |
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