Probabilistic Analysis of the Frozen Depth of Soil Foundations Considering Thermal and Hydraulic Coupling by COMSOL

53.5% of China’s territory is seasonally frozen. Along with China’s fast social and economic development, more and more infrastructure facilities, e.g., railways, highways and hydraulic engineering projects, are being constructed in frozen soil areas. Since foundations are the underpinnings of these engineered structures, the performance of frozen soil foundations is critical to the safe and stable operation of these infrastructures. Frozen soil exhibits strong heterogeneity, which influences the prediction of the engineering performance of frozen soil foundations; however, previous studies have ignored this effect. In this paper, the coupling effect of thermal and hydraulic behavior and soil parameter heterogeneity of frozen soils is considered. A rectangular foundation is taken as an illustrative example, and COMSOL Multiphysics is applied to predict the coupled thermal and hydraulic behavior of frozen soil. Karhunen-Loève expansion is selected to capture the frozen soil parameters’ heterogeneity. Based on the analysis, the proposed framework can successfully calculate the stochastic frozen depth of the foundation. Due to the thermal conductivity’s heterogeneity of soil grains, the depth to which the foundation is frozen changes in a range rather than a single value in the deterministic analysis.