The Prediction And Evaluation On New Landslide Between Yunyang To Fengjie Of Three Gorges Reservoir Area

Three Gorges Project is the maximum water resources and hydropower engineering of China in history, it benefits of flood control, power generation, shipping, aquaculture, tourism, irrigation and some others.It at Sandouping ,Yichang City of Hubei province, the length of it's river and tributaries is about 5311km,the total area of reservoir is about 10000km2.After reservoir,the water level will fluctuations between 175m and 145m,rise fast and flow slowly, the maximum fluctuation will more than 30m. A large number of engineering examples at home and abroad prove that, the reservoir will greatly changed the water circulation system of reservoir, so the hydrogeological conditions of the rock and soil slope changed, in the role of soaking, dig and lift toe erosion by the reservoir water, the composition, structure, strength, stress state of the rock and soil slope will changed, so the new landslide will occurred. According to the information of the reservoirs have been built at home and abroad, the quantity of new landslide after water will reach the number which is the third of the old landslide,so,the new landslid after water will more than hundred,it will threaten Yangtze River waterway, the environment, capacity and economic development and social stability of the Three Gorges Reservoir Area.In this paper, for the study of the landslide prone areas of Three Gorges Reservoir Area, section Yunyang to Fengjie, by means of laboratory study and site survey, on the basis of analysis of regional geological setting and geological conditions in the study area, research the slope structure of this reservoir and do the geological section, and slope failure modes, development of landslides and law, mechanism of formation and evolution of landslide and other are discussed, analysis the influence of reservoir, use process mechanism analysis, evaluation factors, fuzzy comprehensive evaluation method and limit equilibrium, do the prediction and evaluation on new landslide between Yunyang to Fengjie of Three Gorges Reservoir area,here is the conclusion: 1. Analysis the regional geological setting and the geological conditions in the study area of the region, on this basis, give the structure of the region divided into the following types of slope, gently layered slope, lateral slope, layered slope forward, reverse layered slope, oblique layered slope, discussed their deformation and failure respectively,and conducted a geological section on Yangtze River and its tributary. 2. Conducted a study on the development features and formation mechanism of landslide of this reservoir, landslides are mainly developed in J_3p,J_3s,J_2s,J_2xs,J_2x,J_1-2z,T_3xj,T_2b stratums, lithology is mainly sandstone and mudstone or limestone, mudstone or marl, mudstone,in other stratums,it's little landslides; landslides are mainly developed in forward layered slope, especially slow forward layered dip slope, the dip layered slope, landslides are less developed in gently layered slope, reverse layered slope; landslides are mainly developed in concave bank river, the junction of the Yangtze River tributary and other invading areas with better conditions like this.3. Considered the effect on surface water and groundwater systems by the reservoir, detailed analysis of the physical action, chemical action, mechanical effects caused by the water. Analysis shows that the interaction of groundwater and rock and soil slope further exacerbated the original water-rock interaction,even generate a new mode of action of water-rock, change the composition, structure, strength, stress state of the rock and soil slope,so the stability of rock and soil slope will change.4. Identified the evaluation index system of prediction and evaluation about new landslide: lithological, structural type of slope, slope, slope height, the role of geological structure, geological rivers, rock weathering, impact of reservoir water level fluctuation, one-day maximum rainfall, wind (wave) wave function, human engineering activities, using a combination of quantitative and qualitative methods determine the weight of each index value,and use the membership functions and AHP method determine the value of index membership.5. On the basis of the geological survey, use process mechanism analysis, evaluation factors, fuzzy comprehensive evaluation method , limit equilibrium, do the prediction and evaluation on new landslide in the area, evaluation showed that the stability of all the landslides are poor or even worse.