Study On The Mechanism Of Deformation Stability And Control Of High Slope Under Complex Conditions

The complex geological environment in the southwest of China,such as strong earthquake,high geostress,high osmotic pressure and high unloading,makes the deformation stability of high slope outstanding.Field monitoring data show that there will be a continuous nonlinear deformation stage before the failure of slope.It is of great significance to reveal the internal mechanism and evolution rule of the deformation and failure of slope,and to present economic and reasonable reinforcement.Based on the three dimensional nonlinear finite element method,theory and numerical analyses are carried out to study the deformation and failure mechanism of complex high slope,the parameter inversion of rock mass and the dynamic rupture of the structural interface.The main work and results of this thesis are as follows:(1)Based on minimum plastic complementary energy principlel,a unified local and global stability analysis method for high slopes is established in the framework of three-dimensional nonlinear finite element.Compared with classical three dimensional nonlinear finite element methods,the method adopted in this paper can not only obtain the overall safety factor of slope,but also localize the position of failure areas according to the distribution of unbalance force.And then we can judge the possible failure mode of slope,thus effectively reinforcement can be applied.By studying the distribution patterns of unbalance force of several simple slopes,the correlations between unbalanced force and failure mode of the slopes are further illustrated.(2)Taking the unbalance force as the basis of slope failure,the excavation failure mechanism of the right bank slope of Dagangshan is analyzed.The damage areas computed are basically consistent with the actual situation.After the reinforcement scheme is adjusted,the slope deformation tends to be stable,and the Dagangshan hydropower station has been put into operation normally.It is verified that the stability analysis method used in this thesis is effective in analyzing complex slope system.(3)Based on the D-P yield criterion,a slip weakening model is introduced into the three-dimensional nonlinear finite element program TFINE.Combining with the distribution of unbalanced force,it can be used to simulate the dynamic rupture process of rock mass structure.In part it has made up for the shortage of finite element in the study of interfaces(joints,cracks,lining and so on).(4)Based on the failure mode of the right bank slope of Hongshiyan wedge body,a feasible inversion method for physical and mechanical parameters of rock mass is presented.When it is difficult to evaluate the stability of earthquake-induced rock slope due to the lack of shear strength parameters of rock mass,the method can give a relatively reliable result.Based on the physical and mechanical parameters proposed in this thesis,the overall stability of current wedge body slope is evaluated,and the possible failure area of the slope is also shown.The reinforcement measures presented have been identified as a key of the project.(5)The thermodynamic framework of the dynamic damage evolution theory of rock mass structure is carried out,and the Hamilton principle of the dynamic condition of rock mass structure is established.The factors that must be considered for the dynamic damage analysis of the inelastic body are discussed.It provides an improve direction for the dynamic elastoplastic damage analysis model.