Reservoir Water Mechanism And Stability Analysis Of Toppling Slope

The toppling slope is common in the southwest of China,especially in the bank slope of a large number of hydropower projects.Although the slope has produced a serious toppling deformation in the natural state,and the slope surface rock mass is fragmented and bulk structure,but the slope still keeps its own stability,and the deformation response of the slope after the reservoir area is impounded.In the course of the rise of the water level,what conditions or mechanical conditions in the slope have changed to reduce the stability of the slope,so it is very important to understand the deformation mechanism and failure mode of the bank slope during the change of the reservoir water level,which is of great significance to the study of the stability of the tilting deformed bank slope.In view of this,on the basis of the toppling deformation slope as the support project,based on the field investigation and the collection of measured data,the characteristics of the slope stress field are analyzed qualitatively and quantitatively by geomechanics and numerical analysis method,and then the toppling analysis is combined with the characteristics of the rock mass structure and the toppling deformation characteristics of the actual investigation.The reason for the stability of the deformed slope is to study the mechanism and stability of the large deformation or failure of the dumping slope under the action of reservoir water by the physical simulation test and the numerical analysis method.The main research results are as follows:(1)the general engineering geological conditions and the principle of zoning are summarized and summed up.The toppling slope is mainly developed in the deep canyon zone in the southwest,and the condition is good.The lithology of the slope is mainly composed of phyllite,slate,soft rock or soft and hard interbedded interbedding.The toppling deformed rock mass has many deformation phenomena such as bending,breaking,falling and stretching.Generally it can be divided into extremely strong toppling deformation zone,strong toppling deformation zone and weak toppling deformation zone.(2)the dumped rock mass has the "inclined slit type masonry structure",which makes the rock mass in the toppling and falling area of the shallow surface of the toppling slope with "the mechanical deformation effect of the fractured masonry structure" and the "high stress restraint effect" caused by the slope evolution process and keep itself stable.According to the different contact types of rock blocks,they can be divided into positive pressure type,inclined compression type and reverse extrusion type.(3)taking the toppling slope of the Miao and tailing area as the geological prototype,combined with the engineering geological characteristics of the general toppling slope and the structure characteristics of the slope,the experimental model of the tilted deformation slope with the inclined masonry structure is abstracted,and the parameters of the model size and rock dip angle are designed.According to the principle of similarity dimension analysis,the similarity constant of model test is determined,the material selection and matching test of the model slope rock mass are carried out,and the optimal similar material and the corresponding mix ratio are selected by comparing the model test.The aluminum alloy frame model box is selected.According to the needs of the test,the corresponding measuring elements were selected and the layout of the test points was designed,and the water storage plan was determined according to the test purpose.(4)the results of physical simulation test show that good condition is a necessary condition for the deformation of the slope.The instability of the dumping body begins with the foot of the slope,and gradually develops to the upper part of the slope.At the same time,the rear edge of the slope has a tensile crack and traced the development of the original structure surface.When the connection is formed through the slip surface,the slope will be destroyed.Under the disturbance of water storage,the stress of the rock mass is reduced,the effect of high stress restraint disappears,the foot of the slope begins to deform,and the supporting effect of the slope to the overlying rock gradually disappears,causing the overlying rock to collapse and deformation gradually.(5)the reservoir water function of the topped slope is mainly composed of two parts: hydraulic action and physical softening.The hydraulic action is mainly manifested by the interaction of pore water pressure and stress in the slope,which makes the rock mass deformation and structure change in the slope after the water level is raised.The cause of large deformation or failure of the toppling slope after water storage is the change of the stress of the slope rock mass and the change of rock structure under the coupling of water and rock,which makes the slope lose two conditions to maintain its stability,and its deformation mode is a gradual and stepwise small scale collapse.