Previous studies have shown that an accurate prediction of frost heaves largely depends on the pore water pressure and hydraulic conductivity of frozen fringes, which are difficult to determine. The segregation potential model can avoid this problem; however, the conventional segregation potential is considered to be approximately unchanged at a steady state and only valid in an open system without dehydration in the unfrozen zone. Based on Darcy’s law and the conventional segregation potential, the segregation potential was expressed as a function of the pore water pressure at the base of the ice lens, the pore water pressure at the freezing front, the freezing temperature, the segregation freezing temperature and the hydraulic conductivity of the frozen fringe. This expression indicates that the segregation potential under quasi-steady-state conditions is not a constant in a closed system, since the pore water pressure at the freezing front varies with the freezing time owing to the dehydration of the unfrozen zone, and that when the pore water pressure at the freezing front is equal to that at the base of the ice lens, the water migration and frost heave will be terminated. To analyze the possibility of applying the segregation potential model in a closed system, a series of one-sided frost heave tests under external pressure in a closed system were carried out in a laboratory, and the existing frost heaving test data from the literature were also analyzed. The results indicate that the calculated frost heave was close to the tested data, which shows the applicability of the model in a closed system. In addition, the results show the rationality of calculating the segregation potential from the frost heaving test by comparing the potential with that calculated from the numerical simulation results. This study attempted to extend the segregation potential model to freezing soil in a closed system and is significant to the study of frost heaves.

The mechanism of pipe–soil interaction under frost heaving is complicated due to many factors affecting the pipe–soil system. In order to analyze the sensitivity of various pipe–soil interaction influencing factors and highlight the relationship between the factors and the pipe’s mechanical characteristics during frost heaving, a pipe–soil interaction model based on a semi-infinite elastic frozen soil foundation is developed. Besides, the mechanical indices characterizing the influence factors and their change law are emphatically explored. The results show that the pipe stress changes most obviously at the transition region between the frost-heaving and non-frost-heaving regions. The equivalent stress increases nonlinearly with the increase of foundation coefficient, linearly with the increase of frost heave and elastic modulus of pipe, and decreases nonlinearly with the increase of transition length and pipe wall thickness. The peak stress of the pipe increases linearly with the increase of temperature difference. Moreover, the maximum allowable frost heave deformation decreases nonlinearly with the increase of oil pressure. This study helps provide theoretical reference for the adjustment, control, and prediction of stress and deformation in the design of buried pipelines under frost heaving.

With the ongoing intensification of climate warming and human activities, the permafrost on the Qinghai–Tibet Plateau has exhibited a degradation trend characterized by rising ground temperatures and thickening active layers over the years. Particularly in ice-rich permafrost regions, thermal melting disasters, such as ground subsidence caused by thermal melting, pose a significant threat to infrastructure in permafrost areas. Based on monitoring data from the source region of the Datong River, this article developed a calculation model for active layer thickness (ALT) based on underlying surface types. Utilizing an underground ice distribution model established through geomorphic classification and lithological characteristics, in conjunction with the Nelson model, a risk evaluation of thermal melting disasters in the source region of Datong River was conducted. Based on the current warming trend, the future variation trend of ALT was predicted, and thermal stability was evaluated. The results indicated that ALT in the source region ranged from 1.0 to 3.5 m, with a close correlation between ALT and underlying surface types. The overall thermal stability of the source region is relatively satisfactory, yet it is inadequate in high-altitude areas and on bare ground. Compared to bare ground, swamp meadows and alpine meadows offer superior protective effects on the thermal stability of permafrost in the source region.