Limestone Bedding Landslide Formation Mechanism And Stability Research In Three Gorges Reservoir Wujiang River Valley

The Three Gorges reservoir area Wujiang River Basin is located in Chongqing Fuling District ~ Wulong County, A total length of 80 km and the geological environment is poor, development of many landslides, avalanches. Limestone bedding landslide is the most common landslide of instability damage., because of its enormous size,occurrence sudden, harm significant and so on, has become one of the major environmental problems in the Three Gorges Reservoir Geology Wujiang River. Landslide stable condition related to the normal operation of waterways and roads and the safety of residents along the coast.Due to the Three Gorges Reservoir impoundment, destroyed the old landslide original natural equilibrium state,so that making the steady old landslides before water saving revival. Therefore, the study of the limestone bedding landslide development law,mechanisms and Under the Water of the landslide steady state in Wujiang River Valley,has important practical significance for disaster prevention work of the library section.In order to reveal limestone bedding landslide formation Mechanism and stability in the reservoir water effect in the Three Gorges Reservoir Wujiang River Valley.First, the paper based on the summarizes of the results of previous studies, combination of regional geological setting and the characteristics of the new construction activity, analyzes the Wujiang river valley geomorphology and evolution. Then, summarize the development characteristics and laws of limestone bedding landslide and systematic analysis the geological structure type and deformation damage characteristics of landslide,And then study the deformation damage mode of the limestone bedding landslide. Then,combination with the geomechanical analysis and numerical simulation,using the basic model of system evolution and the physical and mechanical test, discusses the limestone bedding landslide formation mechanism. Finally, consider the impact of water level mobilize, application limit equilibrium method and finite element method to analysis the stability of the landslides of two different accumulation condition. By studying the content of the above conclusions are as follows:(1) study area limestone bedding landslide distribution on the spatial with uneven, mainly concentrated in the Tu Kan ~ Wu Long,Tu Kan~ Bai Ma,Fu Ling ~ Bai Tao three regions.Which is within the natural slope of 10~30°,with weak interlayer and airport conditions better decantation, the convex slope inclination becomes convex or concave angle of slope on the most development.(2) the study area limestone bedding landslide can be divided in ANGLED straight level limestone bedding landslide,moderate dip straight level limestone bedding landslide and changed inclination limestone bedding landslide three categories,its deformation damage mechanisms can be divided in slip- curved and slip- tension two types.Slope development dissolution steeply dipping fracture to surface water infiltration and groundwater migration provides a good channel conditions,when the sliding surface through the rear edge of the crack plane often traces its development.(3 To analysis landslide formation mechanism with geological-mechanics and FLAC3 D numerical simulation:The slow dip straight levels bedding landslide due to the valley lower cut,making the original lower valley weak interlayer exposed,exposed weak interlayer constitute effective free surface for bedding slope slippery move,Under the influence of rain and other factors, the toe apparent shear stress concentration,above the slope there is a clear tension destruction,occurs slip-tension type damage; Moderate dip straight levels bedding slope overlying rock layers under its own weight creep along the weak side, but duo to the leading edge disruption,bending deformation,until the anti-slide segment rock was cut,landslides occur immediately;variable angle formation mechanism and moderate inclination is similar,except that the bent portion of the variable angle located in slow steep rock contact zone,and and will not in the bent portion formation a“cut to come forward”to sabotage,generally along the “chair-like”slip front edge directly cut.(4) paper studying the evolution of sliding soil by X-ray diffraction,scanning electron microscopy, pieces of sub-test,water content test and direct shear tests.The results showed that:the evolution of original raw soft rock to sliding soil,clay mineral content increased significantly,rock soil particle size significantly thinner,and with the interlaminar shear which arranged with a certain orientation,physical mechanical properties are also significantly reduced.(5)using limit equilibrium method, finite element method and gray correlation theory which consider the role of library water to analysis two typical landslide stability and sensitivity factors.The results showed that the different accumulation characteristics, making landslide soil permeability coefficient significantly different permeability coefficient smaller Tong Ziling landslide,due to the changes in the groundwater level than library water leves with obvious “lag” phenomenon,making a greater hydrodynamic pressure inside the slip,reducing the stability of the landslide.