Abstract:
Shield tunnels in cross-river water conveyance systems often exhibit a significant reduction in inter-ring pressure after TBM retreat, leading to lining ring rebound and joint deformation.These issues critically influence the tunnel′s waterproofing performance.Thus, a thorough analysis on the rebound mechanism and joint deformation, along with targeted optimization measures, holds substantial engineering significance.This study first investigates the rebound mechanism of the receiving ring (i.e., lining ring at the acceptance section) and establishes a simplified theoretical model for longitudinal inter-ring forces, clarifying the root cause of rebound.Subsequently, a formula for residual inter-ring pressure in the receiving ring is derived, and its evolution curve is plotted using real-world engineering data, providing a theoretical foundation for optimization strategies.Finally, a case study is conducted based on the dual-tunnel project of the Nanjing Jiangxinzhou Sewage Collection System (crossing the Yangtze River′s Jiajiang section).The research results show that the residual longitudinal pressure in the receiving section decreases as the distance between the jack′s acting surface and the receiving end face shortens, with the rate of decline gradually slowing.For the dual-tunnel project, inter-ring bonding measures over a 10-ring range near the acceptance section and optimized simultaneous grouting were proposed.On-site inter-ring strength verification and weld strength analysis have confirmed the rationality and safety of these measures.This research not only provides a feasible optimization solution for the demonstration project but also offers scientific guidance for the design and construction of acceptance sections in cross-river water conveyance shield tunnels.