Study On Formation Mechanism And Evolution Law Of Jinjinzi Landslide In Three Gorges

Wanzhou District is a mountainous area,located in the northeast of Chongqing,where geological disasters occur frequently.Wanzhou District is affected by the Three Gorges Project and has a well-developed water system.The main stream and tributaries of the Yangtze River are spread throughout the Wanzhou District.Therefore,various scales of bank landslides have developed in the Yangtze River Basin in Wanzhou District.The landslides on the banks of the Yangtze River in the Wanzhou area have long threatened the lives,property of the people and waterway safety in Wanzhou District.Due to the flooding of the front edge of the reservoir bank landslide,the engineering geological environment of the slope area has been in dynamic changes.This type of landslide has two key risk factors,namely,water activities and atmospheric precipitation,and its formation mechanism is unique.Therefore,selecting representative landslides in Wanzhou District and studying their formation mechanism and evolution laws can provide theoretical basis for the prevention and control of similar landslides,and can be used as a reference for the study of reservoir bank landslides in other regions.In this study,the Jinjinzi landslide in Yanshan Township,Wanzhou District was selected as the research object.After data collection,on-site investigation,engineering geological survey and mapping,the engineering geological exploration,the geophysical and mechanical characteristics and deformation characteristics of the landslide area were identified.This study also carried out numerical simulation analysis,using ABAQUS finite element analysis software to calculate and analyze the seepage problem of Jinjinzi landslide under the action of reservoir water fluctuation,and through fluid-solid coupling calculation,the initial stage of Jinjinzi landslide was put into use in the reservoir area.The changes in stress,strain,displacement and plastic zone in the phases and the periodic fluctuation phase of the reservoir water level.The main conclusions of this research are as follows:(1)The reservoir water change is one of the reasons for the change of the seepage field inside the slope.The seepage phenomenon at the front edge of the slope is more significant.In the different stages of the reservoir water change,the seepage velocity is different,and the change speed is also different.The seepage effect is extremely complex in areas with large topographical changes.(2)The change of reservoir water level has different effects on slope stability at different stages.In the early stage of the reservoir area being put into use,the slope body experienced the greatest environmental changes,and its overall stability changed significantly.During the period of the reservoir water cycle,the distribution of the stress and strain field inside the slope and the distribution of the displacement area are different,which is characterized by relatively stable overall but continuous deformation.(3)The secondary influencing factor is atmospheric precipitation.The influence of atmospheric precipitation on the stability of the slope varies with the state of the reservoir water level.When the water level is high,the rainfall affects the secondary landslide at the rear edge of the slope,but the rainfall during the discharge period mainly affects the middle and front part of the slope,and it is most significant in the place where the topography changes the most.(4)The formation of the Jinjinzi reservoir bank landslide is based on a cumulative gradual change,and its essence is the collapse of the bank slope-the formation of collapsed deposits and the slippage of the collapsed deposits.With the change of the geological environment and the action of external forces,the slopes continue to collapse and accumulate,thus forming the shore team collective.When it is affected by water activities such as changes in the reservoir water level and atmospheric precipitation,the collapsed accumulation body faces the Yangtze River.The slippage of the channel has formed a landslide,which is essentially a short-term observation result of the evolution process of the bank slope failure.