Numerical Simulation Research of Construction Method for Shallow Buried Large Section Tunnel

The background of this paper is based on Deli tunnel of Xi'an to Chengdu Railway passenger dedicated line. In order to compare and optimize this large section tunnel project under different construction methods, General FEA software ANSYS was utilized to simulate and analyze the stress and deformation in 2-D and 3-D. According to the Deli tunnel engineering case, the preliminary comparison and discussion of mechanical properties and deformation characteristics of the construction of bench cut method and two side-wall pilot tunnel method have been carried out. From this simulation, we made the conclusion for different mechanical properties and deformation characteristics in different construction methods. It shows that the two side-wall pilot tunnel method results in less stress and deformation than the bench cut method. Therefore, it is safer to use the former method. The key step for bench cut method is the upper excavation, and the key step for two side-wall pilot tunnel method is the upper core soil excavation. Monitoring and enhanced support of these key areas is imperative to guarantee the smooth construction.