Stability Of Landslide Under The Effect Of Reservoir Water In The Area Of Fuling Of The Three Gorges Reservoir Area

Fuling section of the Three Gorges Reservoir area is about 85 km.Landslide, collapse and unstable slope are developed in the reservoir because of the effects of construction, river, human engineering activities on the geological section of the library environment. It has become a major geological environmental issues on Fuling Basin of the Three Gorges Reservoir. In the Three Gorges reservoir impounding, increasing the influence of reservoir water drop and human engineering activities, the original natural equilibrium state of the old landslide is destroyed by different degree, which causes the stability of the old landslide to be revived, and its instability and destruction seriously threaten the safety of shipping and the personal property of the residents in the area.Therefore, it is of great practical significance for the disaster prevention and reduction to study the types, development characteristics and the stability of the landslide under the condition of increasing the daily decreasing range of reservoir water level.On the basis of the geology environment condition and field system research in the Fuling section of the Three Gorges Reservoir area, this paper studies development characteristics, development law and types of reservoir bank landslide, and makes the stability calculation and evaluation incense beach No.1 landslide as a typical example. In this paper, the process mechanism method, fuzzy mathematical evaluation method and limit equilibrium method are used to forecast the stability of each landslide under the condition of increasing the daily decreasing range of reservoir water level. According to the above three kinds of evaluation results, the comprehensive prediction landslide stability condition, obtains the following conclusion.(1)According to the material composition and the trend of the rock slope and angle, the reservoir structure is divided into rock slope and soil slope. Rock slope can be further subdivided into nearly horizontal layered slope, slow smooth inclined to layered slope, slow tilt reverse layered slope, oblique layered slope, horizontal layered slope.(2) The correlation between the development characteristics of the landslide and the structure of the slope, landform and the lithology of the strata is studied and analyzed, and the following conclusions are obtained. The quantity of the landslide is decreased in the Gently inclined slope, the reverse slope, the near horizontal slope, the inclined slope and the transverse slope. In the linear slope, the number of the landslide is the most, the concave slope is the second, the other is the least. The natural slope of the landslide is mostly between 10 degrees ~30 degrees, a small amount of less than 10 degrees. The formation of three empty convex faces are more prone to landslide slope. Considering the stratum lithology, slope structure, deformation failure mechanism, wading, slip surface shape and other factors, the study area landslide were divided into float type, dynamic water pressure type, composite type three types.(3)This paper selects incense beach No.1 landslide as a typical example, based on studying the characteristics of landslide, the stability of the landslide is evaluated qualitatively, and used the Geo Studio software seep / W module and slope / W module to simulate the seepage field and stability calculation, then evaluated and predicted the stability of landslide, final get the following knowledge. With the water level of the Three Gorges Reservoir decreased, the free face of the slope in the slope also decreased with time. With the continuous decline of reservoir water level, the lag phenomenon becomes more and more obvious, and with the increase of the reservoir water level decline rate, the lag effect is more strong, the stability of the landslide is getting worse.(4)The stability of the 32 landslides in the study area are predicted and evaluated by using the process mechanism method, the fuzzy mathematical evaluation method and the limit equilibrium method. In the process mechanism method, Hen Liangzi landslide and Da Zhulin landslide, based on the field investigation, the study of deformation, failure mechanism, the history of the evolution of the slope, and the present deformation, considering the influence of reservoir water, are predicted in an unstable state. On the boundary of Bazi landslide as an example, the paper uses fuzzy mathematics evaluation method draw that B = {0.1302,0.2453,0.2951,0.3295} through each factor weight vector and fuzzy relation matrix synthesis operation, and according to the principle of maximum membership degree obtained "the dam slope would be in a stable state" conclusion. Based on listing typical examples and the rest of the landslide stability prediction results,the statistical analysis showed that most of the uplift of landslide stability is better, the dynamic water pressure type landslide most in steady state, the compound landslide generally poor stability ~ poor stability.