Research on Coupling Effects and Collaborative Control of Dewatering in Metro Deep Foundation Pits Adjacent to High-Speed Railways

Aiming at the impact of dewatering in metro deep foundation pits on the deformation and safe operation of adjacent high-speed railway bridge piles, this study investigates the mechanism of pile-soil interaction under seepage-stress coupling effects and proposes effective collaborative control measures. Through field pre-dewatering tests, variations in groundwater levels and surface settlement around bridge piles under different drawdown conditions were monitored. Using Abaqus for numerical simulation, a seepage-stress coupling model was established to analyze the influence of different dewatering depths on the lateral friction resistance and neutral point position of pile foundations, with comparative analysis against field data to summarize variation patterns.As the dewatering depth increases, the disturbed seepage field gradually extends toward the pile foundation, forming a seepage flow pattern around the piles. The deformation of the pile foundation exhibits nonlinear growth, with significant increases in settlement and lateral deformation observed after exceeding a 10 m drawdown. Negative skin friction in the upper part of the pile increases, the neutral point shifts downward, and positive skin friction at the pile base enhances.The deformation of bridge piles adjacent to metro deep foundation pits during dewatering is considerably influenced by the dewatering depth. Collaborative control measures such as multi-stage dewatering, waterproof curtains, real-time water level monitoring, and recharge can be adopted to mitigate pile deformation and ensure the operational safety of high-speed railways.