Study on the Influence of Double-line Shield Tunnel on the Foundation of the Adjacent Elevated Pile

When the shield method constructs the subway tunnel in close proximity to the pile foundation of the existing operating urban rail transit viaduct, the surrounding soil will be disturbed, and the additional stress generated by it will lead to the deformation of the pile foundation, which will bring potential safety hazards to the existing operating urban rail transit. In this paper, the existing Chongqing Rail Transit Line 1 viaduct pile foundation is taken as an example, and the influence of double-line shield construction on the bridge pile foundation under different excavation sequences is studied by using abaqus finite element numerical simulation software. The results show that the maximum surface settlement value is 1.89 mm, and the maximum additional displacement of the horizontal pile foundation is 1.75 mm, and both of them appear near the central axis of the shield. In addition, the closer the shield is to the pile foundation, the greater the influence of the shield tunneling on the pile foundation, and it is recommended that the shield starts the tunnel farther away from the pile foundation first, and then starts the tunnel closer to the pile foundation after the implementation to the safe distance.