The Research For Ground Settlement Caused By Shield Tunneling

Shield tunneling is one of the most important method of tunnel construction, however , it will bring influence on ambience inevitably,especially stratum settlement is very distinct.So it is essential to study the stratum displacement caused by shield tunneling .The thesis has discussed the shield tunneling process and influence of stratum displacement disturber caused by shield tunnel construction. The process of shield tunneling is simulated and all kinds of factors are considered carrying ground settlement by using finite element method. Some rules about Stratum longitudinal settelment, Crosswise settelment and Horizontal displacement are gained.In this paper, with the functions of element birth and death and continuous time steps of the ANSYS finite element software, employing the methods of the rigidity migration and the stress release, the process of shield tunneling,pouring thick liquid into shield tail and lining supporting are simulated. But it difficult to simulate shield tunneling process directly, especially considering shield tail crevice, disturbance to the surface of tunnel and disposeing of pouring liquid. So another shield tunneling simulating method is presented, which transfer some variable (such as shield tail crevice size, the degree of pouring thick liquid and the scope of disturbance on soil around the tunnel surface etc,) closed to construction but hard to scale to isotropic, equal thick layer. The later method not only objectively reflect the influnce of some not easy quantified factors on the surface displacement but also avoids attend to one thing and lose another.So that it can reflect the actual situation of project and simplify the computation model.The influence of tunnel burying depth,the soil physical property,radius of the tunnel excavation, the pressure on the excavated surface as well as the tunnel relative buryed depth to the stratum longitudinal,crosswise and the level to the settelment influence are detailedly analyzed in this paper. Some changing rules which changes with some factors are gained. It is expected that it can take some advice on the project construction.