Abstract: Tunnel temperature fields in cold regions are critical for preventing lining frost damage and ensuring safe operation. Existing analytical heat-transfer models often neglect contact thermal resistance in multilayer support systems. This study develops a transient heat-transfer model for multilayer annular media with arbitrary layers under time-varying boundary conditions, incorporating contact thermal resistance. A semi-analytical solution is obtained using the Laplace transform and transfer-matrix method. The 0 °C isotherm is taken as the freezing radius, and the proposed solution is validated against finite-element simulations and field monitoring data. Results show that contact thermal resistance causes slope changes in the freezing-radius curve at layer interfaces, and neglecting it would overestimate the heat-transfer capacity of the tunnel insulation system. Sensitivity analysis indicates that the maximum freezing radius is most sensitive to air-temperature amplitude and insulation thickness, while contact thermal resistance remains non-negligible for engineering design. Results can provide theoretical guidance for the refined frost resistance design of tunnel insulation structures in cold regions.