| The geological condition of the Three Gorges Reservoir area is complex,and it is a high incidence area of geological hazards.History had due to landslides collapse repeatedly blocked the waterway of the Yangtze River,in the 1980 s happened Xintan Landslide and the jipazi landslide,causing the Millennium ancient town,buried in the riverbed,main channel of the Yangtze River unnavigable ten days a major disaster.After the completion of the Three Gorges project,the water level rise one hundred meters,the annual reservoir operation to form the 30 m water level fluctuation.Great changes in the water level and towns in situ by superposition of artificial relocation and other factors,the disturbance of the geological environment of the reservoir area,the prevention and control of geological disasters facing enormous challenges.1.The work in this thesis analysised of the Three Gorges Reservoir area special engineering geological conditions,terrain is steep and complex structures,precipitation time and space is very uniform,the most important is the cyclic variation of reservoir water level year 145 m to 175 m in.These factors have led to frequent geological disasters in the reservoir area.However,from 08 years,the annual number of new geological disasters has been significantly reduced.2.Taken Liangshuijing landslide as a case study,the landslide is located in the Yangtze River on the right bank slope,the landslide is a typical reservoir landslide.Under the action of reservoir water,there is a certain relation between the displacement and deformation of landslide and the change of water level.Based on 5 days and 10 days of accumulated time window,it is believed that when the reservoir water level rises and falls,the landslide will be deformed.Every year 5 to 6 months of reservoir water level decline rate(0.3~0.4m/d),and every year in June and July for landslide displacement rate of change also will reach annual maxima,the characteristic peaks every year from October to November,reservoir water level average increase rate of reach maximum sliding displacement rate changes a little.3.The thesis uses the Seep/W software to analyze the saturated unsaturated seepage simulation,the results inherit to Slope/W to carry on the stability analysis method,has realized the multi field coupling numerical simulation computation.The simulation results(1)the water level increased from 145 m to 175 m in the process of safety coefficient curve of landslide is on the rise,with the increase of reservoir water level,the FOS increases,indicating water level rise behind the landslides of reservoir water level,thus forming the low high pressure difference to landslide is more stable;(2)the water level rises faster,the FOS increase to the maximum value is faster,the value is high;(3)when the water level rises to 175 m stable water level,as time increases,the water level gradually rose to within the landslide stability level,slope pressure is difference between the inside and outside gradually dissipated,leading to landslide stability decreased;(4)if the water level rises to 175 m stable level after a long enough time,the FOS will be lower than the 145 m value of(5)stable water level;water level decreased from 175 m to 145 m in the process of system stability 40 curve number decreased,with the decline of the reservoir water level,the FOS in the lower water level drops behind that of landslides of reservoir water level,which formed in high low pressure difference makes the landslide is more unstable;(6)drawdown speed faster,the FOS decreased to the minimum value also faster,the value is low;(7)when the water level dropped to 145 m stable water level,as time increases,the internal water level gradually decreased to landslide stability level,landslide pressure difference between the inside and outside gradually dissipated,leading to landslide FOS increased;(8)if the reservoir water level dropped to 145 m stable water level long enough,the FOS will be higher than the 175 m value of the stable water level.4.Through in-depth analysis of 0.2,0.4,0.6,0.8,1.0,1.2,1.4,1.6,1.8 m/day and 2.0 m/day altogether 10 kinds of reservoir rates and the stability of the landslide that: as v=0.8m/d has considerable significance on behalf of rapid decline apid drawdown definition of numerical.When the water level drop speed is greater than 0.8m/d,the safety factor of reservoir landslide is significantly reduced,then increased disaster risk.Combined with numerical simulation and reservoir for many years actual operation curve and establish the reservoir operation and landslide disaster acceptable risk,this paper puts forward three gorges project meet the accumulation landslide stability of acceptable risk variable range(less than 0.6m/d,low risk;0.6m/d ~0.8m/d and risk;faster than 0.8 m / D,high risk for reservoir operation provides scientific basis.Therefore,it can be used to optimize and recommend the reservoir water operation plan for the risk of reservoir landslide in the reservoir area.5.The long-term safety of process safety curve and geological disaster risk level combined,the risk curve of Liangshuijing landslide is given for many years.6,According to the theory of saturated unsaturated seepage,under the condition of non steady flow influence accumulation landslide stability of K,C,phi and reservoir water level amplitude V are simulated and analyzed,that K value of landslide FOS have significant effects.V=0.8m/d can be as reservoir operation reasonable amplitude.7,Through the analysis of the years 2009-2012 Liangshuijing landslide monitoring data,proposed the landslide deformation and evolution,put forward LURR prediction model of landslide accumulation theory of reservoir water level and rainfall effect based on.8,Through the analysis of the impact factors of Liangshuijing landslide,binding site in different slope actual situation and economy,the construction difficulty degree and the time limit of the consideration of the proposed control scheme "cut and load shedding(phased implementation and monitoring and early warning)and drainage engineering,the optimization of comprehensive prevention and control measures and the comparison of the numerical simulation analysis.The results show that the safety factor of the landslide has been greatly improved after the comprehensive treatment.The scheme can be applied to the prevention and control of the landslide in the reservoir area.The innovations of this thesis is blow:1,this study through numerical simulation and analysis of water level changes on the response law of landslide groundwater seepage field,stress field,deformation field and its influence on the landslide stability;2,according to the analysis of the risk of different speed of drawdown conditions of colluvial landslide,the present stage reservoir safe operation of the diurnal variation of acceptable risk was proposed and the result could be theoretical support for the safe operation of the reservoir;3,according to the change of reservoir water level on the landslide risk analysis,optimization of the Three Gorges reservoir accumulation reasonable landslide treatment scheme,provided theoretical support for the safe operation of the reservoir. |
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