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Water-bearing joints within rock engineering in cold areas are often subjected to frost heaving force in cold season due to water–ice phase transition. To evaluate the damage and stability of rock mass in cold regions, a 3D model that considers moisture migration loss during freezing and thawing was established to study the characteristics of frost heaving force within joints. Then, the numerical simulation of cyclic freeze-thawing of water-bearing joints was carried out through equivalent expansion coefficient and particle flow calculation methods. The distribution of frost heaving force in and around the joints was obtained. According to the results of the numerical tests and theoretical calculations, the frost heaving force in joints is basically stable, the tensile stress concentration area appears at the joint tip, and the frost heaving force decreases gradually away from the jointed rock mass area. The frost heaving force decreases considerably with increasing cycle number and moisture migration loss but it increases with increasing mechanical strength and joint geometric size of rock and ice. The comparison between the numerical solution of the equivalent expansion coefficient method and the theoretical solution shows that the force size and distribution law of frost heaving for the two methods are consistent.

To address the severe issue of subgrade frost heave in season-frozen soil highway engineering in the Qinghai-Tibet Plateau (QTP) region, this studied investigated the frost-heaving characteristics (FHC) of subgrade soil with different initial water content (IWC) and fine particle content (FPC) under unidirectional freezing (UDF) and surrounding freezing (SDF) conditions through laboratory experiments. Furthermore, based on the thermo-hydro-mechanical (THM) coupling theory, variations in the temperature, moisture, and stress fields were analyzed numerically. The findings aim to provide a reference for the development of preventive and control measures against subgrade frost heave. The results show that the frost-heaving deformation (FHD) of subgrade soil can be divided into four stages: frost-shrinkage deformation stage, FHD rapid increase stage, FHD slow increase stage, and FHD stabilization stage; A sensitivity analysis suggests that controlling the IWC and FPC at approximately 8% and 9%, respectively, in the subgrade gradation design can effectively inhibit frost heave. Compared to the SDF condition, the UDF condition resulted in a more significant temperature gradient and a distinct freezing front. However, stress concentration points were observed under both freezing conditions

The phenomena of freezing damage in the cold regional tunnels have happened frequently. Therefore, in order to precisely calculate frost heaving force (σ1), based on the displacement method, a new analytical solution was proposed. The analytical solution presented in this paper was verified by the results of the model test and field measurement of σ1, the imperfect contact effect between frozen and unfrozen zones of surrounding rock was considered and the influence of the interaction between any two factors on frost heaving force was studied by means of orthogonal experiment and analysis of variance. The results show that: (1) the inner radius of lining (ra), excavation radius (r1) and freezing radius (rf) are highly significant for σ1 and the interaction between the inner and outer radiuses of lining (i.e., changes of the size in inner and outer radius of lining) is also highly significant for frost heaving force (σ1); (2) the analytical solution presented in this paper can avoid the frost heaving force (σ1) with tensional property under the condition of the circular tunnel under hydrostatic pressure; and (3) sensitivity function shows that the larger Young’s modulus of lining (EI), inner radius of lining (ra), freezing radius (rf), linear frost heaving rate (β0) and Young’s modulus of frozen surrounding rock (EII) are, the more sensitive the factors EI, ra, rf, β0 and EII are to σ1. It is expected that the results of this paper can give some novel insights for the anti-freezing design of tunnels.HighlightsInner radius of lining is the more sensitive to frost heaving force.The interaction between the inner and outer radiuses of lining is highly significant.The ra, r1 and rf are highly significant for frost heaving force.The analytical solution can avoid frost heaving force (σ1) with tensional property.

Landslides occurring under low-temperature conditions in winter with spatio-temporal unexpectedness can result in significant losses of human life and property. At about 5:51 a.m. on January 22, 2024, a landslide disaster occurred in Liangshui Village, Zhenxiong County, Yunnan Province, China, resulting in 44 deaths. This study analyzes the characteristics and discusses the disaster’s mechanism using a combination of on-site investigation, drone aerial survey, remote sensing interpretation, InSAR analysis, and numerical calculation. The results show that (1) the landslide in Zhenxiong was relatively small in volume, approximately 118,800 m3, but with significant consequences of 44 fatalities; (2) the regional factors such as geology, geomorphology, meteorology, and hydrology are conducive to the development of landslide disasters. The landslide occurred near the top of the steep slope with a height difference of 250 m and was in the form of a “boot-shaped terrain.” The lithology of the area consists of siltstone and mudstone of the Triassic Feixianguan Formation, and the vertical joints of the rock body have cracked up to 1.4 joints per meter; (3) before the landslide occurrence, the slope was in a critical state with extensive development of cracks, and a large number of these cracks were parallel and perpendicular to the ridge. The ratio of historical weathering sections in the stone blocks in the accumulation area is more than 60%. InSAR results show that the landslide source area has been undergoing continuous creeping subsidence since 2020, with a maximum displacement rate of − 61.31 mm/yr; (4) three factors contributed to the slope’s freeze-up and destabilization: the catchment at the slope’s back-end, the sandstone-mudstone interlayer’s geology, and the sustained low temperature before the landslide. The low-temperature frost-heaving effect may finally trigger the landslide. Considering the frost-heaving force, the factor of safety of the block was 0.99, and a landslide debris flow with a high-speed rate of 40.09 m/s was formed after the block was destabilized. This type of geological disaster in winter is highly unexpected and requires great attention.

Shear experiments were conducted on the cement mortar–sandstone bonding interface and the materials themselves to investigate their loss of shear strength and the deterioration mechanism caused by freezing and thawing cycles. The experimental results show that the shear strength of the bonding interface is much lower than that of the original materials themselves under the same normal stress. The shear strength of this interface decreases linearly with increasing number of freeze–thaw cycles, but it linearly increases with increasing normal stress. The cohesion and internal friction angle also decrease as the number of freeze–thaw cycles increases. In addition, obvious freeze–thaw debonding of this interface is observed and it is first caused by the difference in frost-heaving deformation between the cement mortar and the red sandstone, followed by the frost-heaving pressure in the crack formed in the interface. Finally, the shear damage of this interface has been quantified by reconstitution of the interface morphology. As a result, almost all the shear breakage occurs on the red sandstone side, and a concave rough face arises. With the absence of normal stress, the shear abscission area in the red sandstone increases quickly with increasing number of freeze–thaw cycles. However, with increasing normal stress, this shear abscission area decreases, and the layered composite specimens were prone to shear failure straightly along the bonding interface, because the shear dilatancy deformation is constrained. This study provides the shear failure characteristics of cement mortar–rock interfaces under freeze–thaw cycles and contributes to a better understanding of the freeze–thaw debonding mechanism of protective cement mortar layers on rock surfaces.

With the vigorous construction of water conservancy projects in the cold regions of western China, the frost heaving cracking problem of rock mass fissures in cold regions under the water-ice phase change seriously threatens the safety of projects. This study aims to explore the fracture laws of rock masses containing random fissures under frost heaving, providing a basis for frost-resistant design and disaster prevention in cold region projects. The study uses the Smoothed Particle Hydrodynamics (SPH) method. A failure coefficient, a discrete format of the heat conduction equation, and an equivalent thermal expansion coefficient method are introduced to build the model. The Monte Carlo method is used to generate random fissures, and numerical simulations are carried out by setting different fissure lengths, numbers, and dip angles. The results show that different fissure lengths, numbers, and dip angles have different effects on the frost heaving failure patterns of rocks. An increase in length makes secondary cracks more likely to overlap, the cracks become coarser, more complex, and their expansion accelerates. An increase in the number of fissures makes the crack distribution denser, the overlapping and merging of cracks accelerate, and they are distributed in blocks. Changes in the dip angle affect the crack direction, finally, through-going cracks can be formed. By comparing with previous experiments, the rationality of the simulation method is verified. Although the SPH method has certain advantages, there are differences between the simplifications of random fissures and the actual situation. In the follow-up, a three-dimensional SPH method should be developed and combined with non-destructive testing techniques to more accurately simulate the frost heaving mechanical behavior of rocks and support the construction of rock engineering in cold regions.

The freezing of unsaturated saline soil is a dynamic water–heat–vapor–salt–mechanics coupling process. Salt–frost heave, resulting from water–vapor–salt transfer, poses a significant threat to the stability and reliability of geotechnical engineering in salinized cold regions. Based on Gibbs free energy theory, a theoretical framework incorporating osmotic and matric potentials for calculating relative humidity was proposed, highlighting the role of solutes in water–vapor transfer. Unidirectional freezing experiments were conducted to explore how salt content, water content, temperature gradients, and freezing modes influence water–heat–vapor–salt–mechanics coupling interaction. The results reveal the coupling mechanism of water–vapor–salt migration, heat transfer, phase transformations between water, vapor, and ice, salt crystallization, and salt–frost heave in freezing unsaturated saline soil. The findings show that vapor diffusion is the primary factor driving moisture accumulation beneath the impermeable layer. Solutes in the pores lower relative humidity, slow the water–vapor phase transition, and hinder vapor diffusion. Water redistribution is influenced by the spatiotemporal variations in water and vapor transfer rates, with a critical moisture threshold required to enhance vapor migration. Below this threshold, vapor transfer becomes significantly more intense. Near the freezing front, overlapping peaks of water and salt concentration create a new impermeable layer due to the accumulation of ice and salt crystals. This process further intensifies water–vapor–salt migration, amplifying salt–frost heave. These findings provide crucial insights into the dynamics of water–vapor–salt interaction and offer strategies for mitigating salt–frost heave in salinized cold regions.

Frozen ground covers vast areas worldwide and about 75% of the land area in the Northern Hemisphere undergoes seasonal freezing and thawing processes. It has been well acknowledged that freeze–thaw cycles (FTCs) and temperature rise in cold regions have significant effects on the hydraulic, thermal, and mechanical properties and processes of foundation soils of infrastructure, which subsequently affect its stability and durability. Numerous efforts have been devoted to mitigate the capillary rise (transport of liquid water under matric potential gradient) to the freezing front that builds up as ice and leads to frost heave, in addition to reducing temperature rise of the frozen ground beneath foundations in order to alleviate thaw settlement. However, increasing more studies have shown that the “canopy effect” would lead to the frost heaving damage and threaten engineering safety given that the capillary rise is minimized and temperature rise is controlled. The “canopy effect” as a result of water vapor transmission through soils or other porous construction materials during ground FTCs that increases ice content beneath the impermeable layer of infrastructure. At present, there is a lack of in-depth and comprehensive understanding of the processes, magnitude, and significance of canopy effect. Therefore, the objective of this study was to review the progress in research on water vapor transport processes in the soil during FTCs, their dominant factors, experimental setup, and control measures. Pros and cons of available water–heat–vapor measurement methods and mechanisms of frost heaving because of water vapor transmission are discussed. Water vapor transmission models are inventoried, the shortcomings of the currently available research are discussed, and future perspectives on water–heat–vapor transmission are also given.

Enhancing the freeze–thaw resistance of cement-based materials in a green and efficient manner is crucial for hydraulic structures in cold regions. This study investigated the effects of soybean antifreeze protein (AFP) on the freeze–thaw durability of cement mortar through mechanical testing, low-temperature microscopy, NMR analysis, and frost-heaving stress monitoring. The results show that AFP improves freeze–thaw durability, with 0.5% dosage outperforming 1.0%. Relative to the control, the relative ice content at −20 °C decreased from 62.81% to 40.01%, and frost-heaving stress declined from 321.15 kPa to 123.04 kPa. Microscopy and pore structure analyses revealed that AFP transforms ice crystals from needle-like to fine granular forms, inhibiting ordered growth and retarding pore coarsening. A frost-heaving stress model based on the Gibbs–Thomson effect and ice-crystal fractal characteristics indicated that AFP suppresses stress development by reducing effective ice formation, weakening stress transfer, and increasing ice-crystal boundary complexity. This study offers insights for developing green antifreeze admixtures for cement-based materials in cold regions.

Freeze-thaw (FT) damage can cause frost heaving and cracking of prestressed concrete (PC) structures, and a decrease in the strain of prestressing tendon, which seriously affects the safety of the structures. An experimental study was conducted to investigate the frost heaving behavior and mechanical deterioration of bonded post-tensioned PC components in an FT environment. The strain variations along the length of the components during 300 freeze-thaw cycles (FTCs) were obtained, and the effects of FTCs and stress levels on concrete frost heaving strain and prestressing tendon strain loss were analyzed. The results indicated that with increasing FTCs, the concrete frost heaving strain, the residual strain, and the loss of the prestressing tendon strain all increased. As the stress level rose, the effect of prestress forces on the concrete frost cracking from inhibition switched to aggravation. Considering the effects of FTCs and stress levels, a strain loss model for the components was established, and it was in good agreement with the experimental results.