Mechanisms and Remediation of Leakage at the Ring Beam in Operating Subway Tunnels

As urban metro tunnels enter the middle-to-late operational stages, water leakage becomes a critical issue threatening structural safety and operational efficiency. Addressing challenges such as the short maintenance windows for operational tunnels and the unclear coupling mechanisms between seepage and structural interactions, this study systematically investigates leakage evolution mechanisms and rapid remediation methods for shield tunnel-ring beam joints in water-rich strata. Firstly, high-precision radar and total station instruments were employed to acquire leakage source data and structural deformation data. Subsequently, a seepage-structure coupling model was established using ABAQUS, revealing critical thresholds including the surface load critical effect (1.44 MPa) and strength degradation of the segment (0.8 times the original strength). Finally, an innovatively developed modified epoxy resin mortar material was applied for grouting remediation, demonstrating significant repair efficacy. The research achieves the first quantification of key leakage evolution parameters and establishes an integrated system encompassing leakage detection, mechanism analysis, and rapid remediation. These findings offer useful insights and a preliminary technical reference for leakage detection, mechanism understanding, and remediation in operational tunnels.