Thermal Response of a Frozen Wall to Freezing-Pipe Failure During Underground Shield Docking: A Three-Dimensional Phase-Change Analysis Evaluated Against Field Measurements

Artificial ground freezing (AGF) is widely used for ground reinforcement and groundwater control during underground shield docking, but freezing-pipe failures can alter the thermal response of the frozen wall. This study examines an ultra-large-diameter shield-docking project in water-rich sandy strata using a three-dimensional transient heat-transfer model incorporating ice-water phase change and comparison with field temperature measurements. At 11 representative monitoring points, R2 ranged from 0.923 to 0.993, and the overall relative error was 6.872%. Under normal freezing, frozen-wall closure occurred at approximately 45 d; the average-temperature criterion (≤−13 °C) and effective-thickness criterion (≥3.9 m) were reached at approximately 54 d and 64 d, respectively. Missing pipes delayed attainment of these criteria to 55–85 d and 84–129 d, depending on their number and spatial arrangement. During shutdown, the average-temperature rise remained below 0.88 °C within 48 h. In the 360 h sensitivity analysis, the rise reached 1.315–2.517 °C for local shutdowns and 4.089 °C for system-wide shutdown. Formation-stage failures were governed by local cooling deficits and neighboring-pipe compensation, whereas shutdown responses were dominated by progressive dissipation of stored cold energy. The results support stage-specific thermal assessment of AGF-assisted shield docking; mechanical stability and excavation safety require separate verification.