Study On Failure Causes And Treatment Countermeasures Of Pengjiacao Landslide In Three Gorges Reservoir Area

This paper takes the Pengjiacao landslide in Xingshan County of the Three Gorges Reservoir Area as the research object,and investigates the engineering geological conditions of the slope.Combined with survey,mapping,theoretical analysis and stability calculation,the characteristics,deformation mechanism,stability,premature failure reasons and the next countermeasures of the landslide are studied.The research results provide important examples and lessons for the development and evolution characteristics of typical landslide geological disasters in the Three Gorges reservoir area and their countermeasures.The paper works as follows:(1)Through the analysis of engineering geology and landslide mechanism of Pengjiacao landslide,it is concluded that the landslide belongs to the creeping step type landslide.The slope is affected by continuous rainfall,and there are many cracks in the upper part.A large amount of rainwater enters the soil through the tensile cracks on the surface,which reduces the mechanical properties of the soil and then causes instability and damage.Rainfall is the main cause of the landslide.(2)Evaluation of the stability of the Pengjiacao trough slope.Through the qualitative evaluation method,limit equilibrium method and finite element method,the deformation and damage situation and stability system analysis of the slope under natural and saturated conditions are obtained.Under the natural working conditions,the Pengjiacao trough slope has a small safety reserve.It is in an unstable state;under saturated conditions,it is in an unstable state,especially under the action of heavy rainfall,the calculated safety factor is significantly lower than the natural working condition.On-site investigation of the slip occurred during the rainstorm season,and some tensile cracks appeared.The analysis results were in good agreement with the actual situation.(3)Research on landslide control measures,and recommend the use of anti-slide pile + drainage ditch + cutting method.The numerical simulation method is used to optimize the parameters of the pile.The results show that under the action of anti-slide pile retaining,the displacement and strain value of the slope are obviously reduced,and the deformation of the pile top is less than the allowable threshold,which meets the requirements of the specification.After the treatment,the slope stability is greatly improved and is in a stable state.