Frost damage on infrastructure in seasonally frozen regions is mainly caused by the coupled water-heat transfer during freeze-thaw processes. Because of complex geological deposition and weathering, the properties of seasonally frozen soil are spatially variable. In this study, based on random field theory, heat transfer process, and frozen soil physics, a water-heat coupling model is developed to explore the impact of non-uniform thermal parameters on soil water-heat behavior. The statistical characteristics of the water-heat behavior and frozen depth of a slope are analyzed. The simulation results show that the water-heat coupling process of the soil exhibits obvious seasonal differences. The uncertainty in thermal conductivity has a greater effect on soil waterheat state than the uncertainty in volumetric heat capacity. The maximum frozen depth (MFD) from the traditional deterministic analysis is slightly smaller than the mean value of analysis result considering the nonuniformity of thermal parameters; as such, the deterministic analysis is likely to underestimate the MFD, which may result in local frost damage to infrastructure in cold regions. To ensure the safety of infrastructure in cold regions, the most unfavorable conditions need to be considered, and the upper bound of the MFD based on the random analysis can serve as the guideline for frost protection design.

The deformation and damage to seasonal permafrost roadbeds, as seasons shift, stems from the intricate interplay of temperature, moisture, and stress fields. Fundamentally, the frost heave and thaw-induced settlement of soil represent a multi-physics coupling phenomenon, where various physical processes interact and influence each other. In this investigation, a comprehensive co-coupling numerical simulation of both the temperature and moisture fields was successfully executed, utilizing the secondary development module within the finite element software, COMSOL Multiphysics 6.0. This simulation inverted the classical freezing-thawing experiment involving a soil column under constant temperature conditions, yielding simulation results that were in excellent agreement with the experimental outcomes, with an error of no more than 10%. Accordingly, the temperature, ice content, and liquid water content distributions within the seasonal permafrost region were derived. These parameters were then incorporated into the stress field analysis to explore the intricate coupling between the moisture and temperature fields with the displacement field. Subsequently, the frost heave and thaw settlement deformations of the roadbed were calculated, accounting for seasonal variations, thereby gaining insights into their dynamic behavior. The research results show that during the process of freezing and thawing, water migrates from the frozen zone towards the unfrozen zone, with the maximum migration amount reaching 20% of the water content, culminating in its accumulation at the interface separating the two. Following multiple freeze-thaw cycles, this study reveals that the maximum extent of freezing within the roadbed reaches 2.5 m, while the road shoulder experiences a maximum freezing depth of 2 m. A continuous trend of heightened frost heave and thaw settlement deformation of the roadbed is observed in response to temperature fluctuations, leading to the uneven deformation of the road surface. Specifically, the maximum frost heave measured was 51 mm, while the maximum thaw settlement amounted to 13 mm.