Numerical Analysis on Large-Section Pipe Jacking within Close Distance in Soft Soil

Three parallel large-section tunnels within close proximity were constructed by pipe jacking to build the Jing'ansi station of Shanghai Metro Line 14. The three tunnels include Tunnel A, Tunnel B, which is on the left of Tunnel A, and Tunnel C, which is on the top of Tunnel A. Cross-section size of the three tunnels is 9.90 x 8.70 m, 9.90 x 8.70 m, and 9.50 x 4.88 m, respectively. Because such large-section pipe jacking in soft soil is rarely reported, a three-dimensional numerical model was developed in this study to simulate the entire construction process of pipe jacking to provide guidance for the engineers. Numerical simulation results demonstrated that the construction of the current tunnel obviously affected the internal force of the previously constructed tunnels. The deformation of the ground surface and the lateral displacement of the neighboring pile groups increased gradually in the process of constructing Tunnels A and B but increased slightly in the process of constructing Tunnel C.