The Study On Soft Rock Deformation Of Deeply-buried Tunnel In The West Rout Of South-to-North Water Transfer Project

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 rock mass in the soft rock tunnel is obtained by experiments, and then on the basis of theory analysis and numerical simulation, the deformation of soft rock tunnel is researched thoroughly, and the comparison between the value of theories calculation and that of the numerical simulation is carried at last. The detailed research result is as follows:Firstly, on the basis of material research of indoor experiment and field test data, and associated with the experiential analogy, the control parameters of the soft rock tunnel is studied and the more reasonable physics mechanics parameters is given, providing a reliable parameter ground for the theory calculation and the numerical simulation.Secondly, through the analysis of primary deformation influencing factors and the deformation character of the surrounding rock, the deformation mechanism of soft rock in the west route runnel project is concluded. The soft rock tunnel project in the west route can be considered as plane strain problem, and 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 , cohesive strength and internal friction angle etc, the effect of surrounding rock deformation is studied theoretically.Thirdly, 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. The influence of physics mechanics parameters of each rock mass to the deformation of surrounding rock in the tunnel is obtained by the elastic-plastic theory analysis and numerical computation to the different combination patterns of rock physics mechanics parameters, which provides valuable reference to the engineering design and field construction. Based on the theoretical analysis and combined with the deformation law, the deformation mechanism of soft rock is further analyzed: excavating tunnel in the soft rock, due to the release of potential stress in the rock mass or the suction expansion of rock mass, the rock is expelled gradually towards the inner of tunnel along boundary. From the result of numerical simulation, it can be discovered that the rock mass around the cavern wall is firstly damaged by the shearexpansion 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.Fourthly, through the comparison of the max displacement values of tunnel between the theoretical analysis and numerical simulating calculation, the following conclusion can be got: under the condition of the same supposing and parameter, the value received by both methods is almost the same.Taking the soft rock tunnel of the west route as the research object, this thesis deploys more thorough study on the soft rock deformation. The thesis has specific project background. Studies show that the soft rock deformation have vital position in the design and construction of the west route.