Research on the Impact of Shield Tunneling on Adjacent Pile Foundation Using FEM

Evaluation of the impact of tunneling on the stability and integrity of the existing pile foundations is a key factor affecting the tunnel safety. The Chengdu Metro Line mainly passes through water-rich, sandy, cobble stratum which has characteristics such as loose structure, poor self-standing ability, and no cohesive force. Therefore, there are no precedent projects for reference. Based on the Chengdu Metro Line 1 adjacent to the airport overpass, numerical simulation was carried out to study the excavation-induced pile response. In numerical simulation, a three-dimensional finite element model was established to study the behavior of pile foundation to adjacent tunneling in the lateral direction of pile foundation. The numerical analyses have included the inherent relationship between the internal force of the pile foundation, the frictional force, and the deformation of the pile foundation during shield tunneling. The results show that the impact on the pile foundation lies mainly in the influence of the shield tunneling on the side-friction force and the tip resistance of pile foundation. It can be found that an inherent relationship exists between the internal force, side-friction force and the deformation of pile foundation, which is of great significance for the assessment of the impact of tunneling on the stability and integrity of the adjacent pile.