Analytical Method for New Tunnel Crossing Pile Foundation of Existing Bridge: a Case Study

This paper describes an analytical method for investigating the tunnel–pile interaction for new tunnels crossing the pile foundation of the Shenzhen Bay Bridge, with a case study using a cavity expansion-based model. The three-dimensional analytical model developed in this study evaluates the ground deformation and pile response induced by the construction of tunnels for the two Metro #13 lines and the Wanghai Road tunnel, and assesses the effectiveness of mitigation measures such as ground stabilisation and isolation walls. The study reveals significant vertical displacement and surface settlement caused by the Wanghai Road tunnel, and horizontal deformation and bending moments in specific pile foundations. The results show that reinforcement measures can effectively control formation deformation disturbance, and metro jet system isolation walls can limit horizontal and vertical displacements caused by excavation. To ensure the safe operation of the Shenzhen Bay Bridge, the study highlights the importance of comprehensively evaluating the safety of shield crossing schemes. The proposed analytical method could also serve as a pre-design tool and reference for optimising tunnel construction, providing valuable guidance for future reinforcement schemes. In general, this study provides significant insights into the tunnel–pile interaction, which will be useful for bridge and tunnel engineering design and construction.