Study On Upper Bound Method For Supporting Force Of Shallow Tunnel Face

:The face of the tunnel is prone to collapse in the tunnel excavation process, how to ensure the stability of the tunnel face is the top priority of the tunnel construction. Based on the limit analysis theorem, the stability of the tunnel face is studied in this paper.1. Using limit analysis theorems failure criterion based on a linear Mohr-Coulomb, a double logarithmic spiral failure mechanism for shallow tunnel face is constructed, and the lateral pressure coefficient is calculated; the effect of each parameters on lateral pressure coefficients are the discussed.2. Based on the previous chapter, the upper bound theorem of limit analysis based on nonlinear Mohr-Coulomb criterion is used to derive the expression of lateral pressure for tunnel face and the impacts of various parameters on the lateral pressure and the shape of mechanisms are studied.3. Relying Shuikoushan tunnel project, the results of numerical simulation by FLAC3D are compared with the analytical method to prove the validness of the method in this paper.