Study on the disturbance law of the new viaduct pile foundation construction to the subway in the adjacent operation

During the construction of elevated bridge pile foundations, the mechanical processes, including the extrusion and friction caused by the steel casing's rotation into the soil and the soil pressure unloading due to soil extraction from pile holes, can significantly disturb existing structures. To address the engineering challenge posed by the planned elevated bridge on Yuanjiang Street Expressway in Shenyang, which is adjacent to the operational Metro Line 10 Dingxianghu Station, this study investigates the disturbance laws of the pile foundation construction on the mechanical behavior of the subway station. A three-dimensional finite element model of the target project was constructed, and numerical simulations were conducted, with a focus on the stress transfer phenomenon caused by friction between the casing and the soil during rotary excavation. The disturbance laws of pile foundation construction on the nearby operating metro structure and the surrounding soil under different excavation sequences were analyzed. The results indicate that the extent of soil settlement is inversely proportional to the distance from the pile foundation; the maximum compressive stress on the top of the station is 2.23 MPa, and the maximum tensile stress at the bottom is 1.31 MPa. The disturbances to the subway station caused by symmetrical drilling, row drilling, and skip pile drilling decrease in that order. The maximum lateral displacement of the subway station is reduced by 57.2% and 26.6% compared to the case without changing the excavation sequence. The study provides insights into the disturbance laws caused by the mechanical transmission path formed by soil friction during the rotary excavation of new elevated bridge pile foundations near operating subway station, offering theoretical reference for future similar engineering projects.