Analysis of tunnel face stability with advanced pipes support

Abstract

To keep the tunnel face stable is very important for tunnel construction. In this paper, the tunnel face stability under the advanced pipe was analyzed using the Winkler foundation model and rigid limit equilibrium. The tunnel face deformation characteristics were also analyzed using the numerical simulation. The influence of parameters on the deflection of the pipe roof and the stability of the tunnel face were discussed. The results show that the tunnel face stability can be improved through increasing the pipe diameter, decreasing the initial displacement at the beginning of the pipe seat, and adopting the short round length and small excavation height. With the increase of tunnel burial depth, the safety factor of tunnel face stability first decreases, then increases, and then remains unchanged. The deformation at the center of the tunnel face is larger than the deformation at the surround sides and at the corner. The horizontal displacement varies little with the increasing of the pipe length. The horizontal displacement at the center of the tunnel face increases with the increase of the pipe ring spacing and the pipe longitudinal spacing. There is an optimum external angle.