Performance of New Tubular Roof Construction Method – A 3D Numerical Investigation

Tunnel construction in urban area inevitably affects the work performance of adjacent infrastructure. Thus, it is of practical importance to minimize the tunneling induced settlement. Selecting an appropriate construction method for urban tunnel projects in soft ground is an important factor for successful implementation of the project. This paper investigates the New Tubular Roof construction method used for underpass project, which is passing underneath the railway station. Based on a series of numerical simulation, this paper studied the ground surface settlement during the pipe-jacking and excavation stage under the different cross-section conditions. Research indicates that the maximum ground surface settlement for the rectangular and arched shape tunnel are 10.66mm and 13.84mm, respectively. Arched shape tunnel induced larger ground surface settlement compared to the rectangular tunnel. For the rectangular shaped tunnel, the amount of surface subsidence caused by the pipe jacking reaches 69.5% of the total settlement, while the amount of settlement occurred in the excavation stage is only 30.5%. In the arched structure, the amount of surface subsidence caused by the pipe jacking reached 54.9% of the total settlement, while the excavation stage of the settlement accounted for only 45.1%.