Finite-element analysis of tunnel face reinforced by longitudinal pipes

This paper presents the results of finite-element analyses on the behavior of tunnel face reinforced by longitudinal pipes. A 3D finite-element model was adopted in this study to capture the 3D behavior of tunnel face under various boundary conditions. A parametric study was performed on a wide range of boundary conditions with emphasis on the effects of reinforcement parameters such as density (number), length, and stiffness of reinforcements on the deformation behavior of tunnel face. The results indicate that the face reinforcement technique using longitudinal pipes can significantly reduce the face deformation, and thus improving the face stability. Also revealed is that there exist a critical value of each reinforcement parameter for which maximize reinforcing effect can be derived. Implications of the findings from this study are discussed in great detail.