Study On Mechanism And Stability Of Yangjiaba Landslide In Yunyang County Of Three-Gorges Reservoir

The second stage program of large geohazards control and prevention in the reservoir of Three-gorges has almost completed, and the third stage geohazard prevention program is going, With the storage of Three Gorges Reservoir, every area of reservoir banks, including the landslide hazard and some old landslide. The stable status of reservoir banks at present and after the storage of Three Gorges Reservoir is vital to the safety of resettlement and reconstruction region, Now the job of constructing the new city has been carrying on. The stability of the yangjaba landslide in Yunyang section will directly influence the process of the new city's constructing and the normally operation of the whole Three Gorge hydraulic project.The key problem of "Reservoir Slope Stability" is the interaction between slopes andimpounded water. By studying the international extent of reservoir slop, On the basis of the investigation in situ and the analyzing of the datum collecting, this paper studies the dynamic character of the groundwater seepage field and thoroughly demonstrated the change character of the stability of the landslide bank in Yunyang section during the process of water storing of the Three Gorge reservoir. The result provides scientific basis for the city's constructing.Based on the survey of geological conditions triggering yangjiaba landslip and features of the landslide and through varied reconnaissance means, this paper, starting with comprehensive analysis of its geological surroundings, thoroughly discusses how the landslip comes into being, its inducing factors and collapse causes. In view of the fact that analysis of a landslide stability is influenced by varied factors and a single method has certain limitations, the paper attempts to introduce the analogy of engineering geology and limited difference into the stability analysis of landslip, on the basis of analogical analysis of comprehensive engineering geological conditions for landslide stability and combined with methods of limit equilibrium and limited difference and finite element methods, makes further analysis and assessment for the landslide's stability and the distribution characters of strain and stress field under different working conditions The result shows the landslide of yangjaba is still stable with the storage of Three Gorges Reservoir and rainy season coming, the sublevel slip mass of the-middle of landslide will slide. So the sublevel section must be controlled.On basis of the concrete character of the whole reservoir bank, the reconstruction of reservoir bank is valuated and forecasted by means of analogy method, which means to acquire the ultimately stable slope angel of zone being affected by reservoir water after reservoir storing water by analogy to the slopes' configuration parameters of the Yangtze River before the reservoir storing water. level to 145m and 175m, The forecasting result shows the reservoir bank being strongly reconstruction when the storing water level is 175m, the total length of bank-collapsing will be 106m.