Numerical Analysis of Large Pipe Roof Support Reinforcement in Shallow Expansive Loess Tunnel

Xiaohegou tunnel is an under construction shallow expansive loess tunnel with Large Pipe Roof Support. Large Pipe Roof Support construction and excavation of the tunnel was simulated by the Fast Lagrangian finite difference software Flac3D. The pipe roof loading states and the deformation of surrounding rock in front of the tunnel face was obtained in each step of excavation, and the results was compared with a simulation without Large Pipe Roof Support. The results show that the reinforcement effect of Pipe Roof was to restrain the plastic flow of soft soil, and Pipe Roof help to share soil pressure, which could decrease the tunnel deformation effectively.