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.

When the shield machines are constructed in soft soil, excavation may be impeded by the accumulation of cutter head mud. Geological conditions and shield construction are identified as the main factors for cutter head mud formation, based on analysis of its mechanism. In addition to traditional metrics, the imperforation area in the cutter head center is incorporated into the analysis of shield construction factors. The Analytic Hierarchy Process (AHP) is utilized to establish a risk assessment model for shield cutter head mud cake, determining the weight of each sub-factor and enabling a preliminary risk assessment of mud cake occurrence. This study applies Analytic Hierarchy Process (AHP) to classify the factors affecting shield mud by using the Mawan cross-sea channel construction project (Moon Bay Avenue along the Yangtze River) as a case study. Each factor is scored and weighted according to established scoring criteria and evaluation formulas, and then the results of the risk of shield mud cake in the Mawan tunnel are obtained. Moreover, field observations validate the proposed risk model, with the derived risk index demonstrating strong alignment with actual data.