Study On Internal Shear Restraint Mechanism Of Deformation And Instability Of Compound Slope

With the rapid development of water conservancy and hydropower engineering construction,there are more and more landslide disasters in the process of engineering construction and operation.Affected by the genetic mechanism and topography,the slope with "gentle front and steep back" is common in the reservoir area.The particularity of this kind of slope is that it has a compound bottom sliding interface.When the upper slope is deformed and sliding,its movement direction will turn,and this kind of turning is at the cost of forming a new shear fracture surface inside the slope.In this paper,the internal shear restraint mechanism of compound slope is studied systematically.The main research object is the vajont landslide,a typical " gentle front and steep back " compound slope.The method of combining theoretical analysis and numerical simulation is used to explore the formation mechanism of shear fracture surface inside the slope and the resistance of the slope to shear deformation,the contribution of the capability to the overall stability of the slope,and the influence of the mechanical parameters on the shear fracture surface.Finally,the method of this paper is applied to the practical engineering case,and its stability is evaluated scientifically.The main research contents are as follows:(1)Through consulting the relevant literature of the vajont landslide event,based on previous investigation and research,the occurrence of the event is systematically studied.The research work on the geological background,the value of sliding zone parameters,the instability mechanism and the failure process of the event is systematically combed,which provides the basis for the research on the internal shear restraint mechanism in this paper.(2)Under the theoretical framework of rigid body limit equilibrium method,considering the internal shear constraint mechanism of compound slope,an analytical analysis method for solving the safety factor of slope with three inclined surfaces is established,which can simultaneously obtain the position of shear fracture surface.Based on this method,the influence of slope resisting shear fracture on the overall stability of slope is explored through parameter sensitivity analysis,the influence of the mechanical parameters on the shear fracture is discussed.(3)Discontinuous deformation analysis(DDA)is used to study the formation mechanism of internal shear fracture surface.By establishing DDA model of vajont landslide,the process of landslide instability is repeated,and the whole process of landslide deformation and failure evolution is obtained,which shows the formation process of shear fracture surface.(4)Taking Zaogutian dangerous rock mass in Wudongde Hydropower Station Reservoir area of Jinshajiang River as an engineering case,the stability under different working conditions is studied combining theoretical calculation and numerical simulation.