Research On The Mechanical Behavior Of The Surrounding Rock In Deep Slates Tunnel

The deeply-buried water tunnel in the west route of South-to-North Water Transfer Project is taken as background in this thesis. Firstly, the physics mechanics parameters of the slates in the rock tunnel is obtained by experiments; and then the creep properties under long time is studied by experiments, the creep constitutive relations were obtained and the parameters were achieved; finally, on the basis of numerical simulation with FLAC3D, the deformation of slates rock tunnel is researched thoroughly, and the surrounding rock stability of the tunnel is carried, the mechanism of deformation and failure was discussed at last. The detailed research result is as follows:Firstly, on the basis of material research of indoor triaxial compression experiment , and associated with the experiential analogy, the control parameters of the slates tunnel is studied and the more reasonable physics mechanics parameters is given, providing a reliable parameter ground for the numerical simulation.Secondly, through the uniaxial and triaxial creep experiment, the creep properties were studied, the creep constitutive model was ascertained, and the creep parameters were confirmed, providing a reliable parameter ground for the numerical simulation. Thirdly, the slates tunnel project in the west route can be considered as plane strain problem, using the physics mechanics parameters, the law of nonlinear deformation such as: stress and strain status, the deformation value, the distribution of plastic zone etc, is studied through numerical simulation. Then the elastic-plastic theory is used in the stability analysis, and the formula of surrounding rock displacement is obtained. Through the sensitivity analysis of parameters such as embedded depth, tunnel radius and the lateral pressure coefficient etc, the effect of surrounding rock deformation is studied, which provides valuable reference to the engineering design and field construction.Fourthly, the law of nonlinear deformation such as: stress and strain status, the deformation value, the distribution of plastic zone etc, is studied through visco-elasto-plastic theory, and compared with the values of elasto-plastic theory. The results showed that the rheology of slates tunnel is obvious.Finally, through the comparison of the max displacement values of tunnel between the elasto-plastic theory and visco-elasto-plastic theory, the following conclusion can be got: under the condition of the same supposing and parameter, the value received by visco-elasto-plastic theory is twice that received by elasto-plastic theory. And it can be found that the rock mass around the cavern wall is firstly damaged by the shear expansion of compressive stress, and then the damage is developed to the deep of surrounding rock. And the expanding of cracks in rock and the volume expansion may happen step by step, and the bending of rock mass around the cavern will occur, the bending tension stress will exist, which in the end cause the deformation failure of the tunnel rock mass.