The Numerical Simulation Of Geological Applicability Of Spoke Wheel

With the process of urbanization is getting faster, because of many advantages in underground traffic, the underground constructions are established by the modern city, and subway is already a hotspot for the urban space to develop coordinately. Shield tunneling technology is a major method in the tunnel construction because of many advantages such as mechanization, minor influence to the surface structures, adaptive in the complex formation and little impact on the environment.The stability of the excavation face is the key problem of the shield method, and the instability of the face is dangerous for the surrounding environment. So scientific workers local or overseas tunneling field are focus on how to keep the excavation face stable and drive safely and efficiently. The main factors of face stability contain the different construction processes, complex geological parameters and various types of cutter heads. Instability mechanism is complex. So far, value of the support pressure is often deduced through the engineering experiences.At present, the main cutter heads consist of spoke wheel and panel wheel. Spoke wheel has lots of advantages such as lightness and low cost, the most important one is the support pressure is easy to control. Thus, it has extreme advantages in projects. In contrast with the panel wheel, the supporting performance of spoke wheel is smaller because of the larger aperture opening ratio, so if the spoke wheel is used depend on whether the excavation face is stable when tunneling the shield. Therefore, the paper researches the geological applicability of spoke wheel and corresponding support pressure in stable tunneling shied by the numerical simulation.In the paper, the soil model is established by the finite element software ANSYS/LS-DYNA. In the course of the numerical simulation research on face stability in spoke wheel tunneling, taking the soil's nonlinear behaviors into account, the simulation uses Arbitrary Lagrangian Eluerian(ALE) formalism to solve the problem of finite element mesh distortion in soil, besides, the material parameters and yield criterion is based on the geological survey and construction reports of NO.3 line of Tianjin subway. Through the finite element simulating geological applicability of the spoke wheel in muddy cohesive soil of Tianjin, the geological applicability of spoke wheel and the threshold support pressure was obtained and compared with the actual construction.According to the parameters of typical soil in NO.3 subway line, the paper concludes the corresponding surface displacements of different moisture content and cohesion when the support pressure is constant.The numerical simulation method in this paper could be applied to research the face stability and corresponding support pressure in the different geological conditions and various cutter heads.