Numerical simulation method for thermal-seepage coupling in artificial ground freezing using liquid nitrogen under high-seepage conditions

• A thermal-seepage coupling model for artificial liquid nitrogen freezing was proposed based on SFCC data. • Accurately simulates freezing under high seepage conditions. • The prediction error is kept below 5 % in both no-seepage and high-seepage cases. • Outperforms traditional EPM in accuracy and efficiency. • Enhances AGF reliability in high-permeability formations. Using SFCC measurements obtained via nuclear magnetic resonance, a temperature–pore ice content relationship was established and a numerical simulation method for a thermo-seepage coupling model that accounts for high-seepage effects was developed. The method’s performance was evaluated by comparing results to an analytical solution for a single-pipe liquid nitrogen freezing scenario without seepage and to experimental data from a three-pipe freezing model under high-seepage conditions. Additionally, the approach was compared to the conventional Enthalpy-Porosity Method (EPM). The results show that: under no-seepage conditions, the numerical model predicts temperature distributions and freezing front radii with deviations below 5 %; under high-seepage conditions, the temperature discrepancy between simulation and experiment remains within 2 °C. Compared to EPM, the proposed method significantly reduces errors in closure time and computation time across seepage velocities ranging from 2.5 to 15 m/d; moreover, at high flow rates, the freezing wall maintains a nearly horizontally symmetric closure, avoiding the offset and distortion observed with EPM. This method enhances the accuracy and physical consistency of artificial ground freezing (AGF) simulations under high-seepage conditions, while also improving numerical stability and computational efficiency, thereby providing a more reliable tool for engineering design and safety assessment of liquid nitrogen freezing in high-permeability formations.