Research On The Toppling Deformation Conditions Of Massive Rock

In the mountains and canyons of the reservoir area,the bank slope occurrence complex environment,outstanding stability problems,is one of the most important issues of hydropower engineering geology.Laxiwa hydropower Guobo slope is a giant rock deformation which controlled by a variety of structural planes,with toppling deformation is the main form.Since the slope resumed deformation after reservoir storage,the displacement of the platform has more than 40 m,is rare at home and abroad.Based on the research of geological conditions and failure characteristics,using a variety of methods,such as geological analysis and numerical simulation,to study the toppling conditions of Guobo bank slope in detail.Finally,analyzed the development trend of the deformation.The research obtained the following understanding.(1)The structure surfaces which controlled Guobo slope’s deformation and damage are taken into four groups:(1)NE30°/NW∠60~80°,(2)NNW~SN/NE~E∠60~70°,(3)NE30~60°/NW∠<40°,(4)NE30~NW340°/SE~SW∠20~35°.(2)When cut to the modern river valley elevation,the stress of slope differentiation significantly,the stress reduced area in which development deep,the horizontal distribution of high elevation depth is 180~220m,low elevation 70~120m,the maximum principal stress values ??is 0~6MPa.(3)Slope deformation and failure is serious,visible in the shore terrace,fore slope and adits,mainly for toppling deformation.(4)The toppling condition of massive rocky slopes including terrain conditions,physical and mechanical parameters of rock,rock structure and stress conditions.(5)The toppling condition of Guobo bank slope including environmental geological conditions and structural conditions of the slope.Environmental geological conditions are: The slope is high and steep terrain,and convex;good overhead conditions to the leading edge and slope inside;higher strength and stiffness of rock,and its prone to brittle failure under unloading condition;situ stress magnitude is higher and the maximum principal stress direction nearly parallel to the slope.Structural conditions of the slope are: Steep slope structural surface within the group(2)steeper inclination,smaller spacing;the group(1),(2)structure in the vertical plane wedge constitute a combination of different depths and sizes,which control of cracks inside the shore fall outside the crack pour offshore decline;the group(3)structure in the advantages of multi-surface inclination angle of the range of 15~25 °,and greater connectivity rate;at about 2700 m exist the angle fault Hf104.(6)After the water level reached 2448 m,slope deformation has stabilized.In the future course of operation of the reservoir,the slope deformation and failure may be localized,but the possibility of a smaller overall instability.