The temperature effect on the mechanical behavior of saturated clay is closely related to overconsolidation ratio (OCR), and there is also a certain interaction between temperature-induced softening and hardening effects. Although existing thermomechanical models can describe the relationship between OCR and temperature, thermosoftening and thermohardening are generally considered as two independent physical mechanisms in theory. Based on the UH model, a new fractional-order thermo-elastoplastic model is established by incorporating the proposed temperature-dependent yield criterion and a non-orthogonal flow rule. This yield criterion is derived from critical state theory and skillfully incorporates the characteristic features of the clay's critical state. The key lies in not only reducing the size of yield surface through the thermal softening effect, but also inducing plastic hardening due to the generation of additional plastic volumetric strain, thereby altering the shape of yield surface. On the other hand, the non-orthogonal flow rule can characterize the effect of temperature on the plastic strain increment direction by establishing a functional relationship between fractional order and temperature. Through comparative validation with experimental results from five types of clay, it is demonstrated that this model can not only effectively simulate the shear behavior and heating-cooling induced deformation of overconsolidated clay under non-isothermal conditions, but also successfully reveal the influence mechanisms of loading hardening/softening and shear strength under the interaction of OCR and temperature. Furthermore, this model successfully extends non-orthogonal elastoplastic theory to the thermo-mechanical domain, providing a theoretical foundation for simulating the mechanical behavior of clay in complex environments.

To study the changing law of compressive strength for concrete with different saturation degrees, water, sodium chloride (NaCl), and sodium sulfate (Na2SO4) solutions are used to erode concrete specimens. Concrete specimens with 0%, 20%, 40%, 60%, 80%, and 100% saturation are obtained, and freeze-thaw tests with different numbers of freeze-thaw cycles (0, 30, 60, 90, 120, and 150 times) are conducted. Axial stress-axial strain curves are obtained by uniaxial compressive tests. The test results show a significant reduction in uniaxial compressive strength and an increase in axial peak strain with increasing saturation level. Following 150 freeze-thaw cycles, the strength loss rates for the water, NaCl, and Na2SO4 solution groups are 7.9%, 13.2%, and 29.7% for low (20%), 10.6%, 20.1%, and 41.7% for medium (60%), and 10.1%, 22.0%, and 45.9% for full (100%) saturation, respectively. The corresponding increases in axial peak strain are 22.9%, 39.1%, and 41.9% for low saturation, 21.4%, 29.8%, and 54.0% for medium saturation, and 17.0%, 34.4%, and 65.4% for complete saturation. It can be observed that the erosion of NaCl and Na2SO4 solutions results in more serious degradation of concrete strength. Freeze-thaw cycles further exacerbate the degradation of concrete strength, especially at high saturation levels. In this paper, a prediction model based on the binary medium strength criterion is proposed, which can effectively predict the strength of concrete after freeze-thaw cycles.

The variation of unfrozen water content with temperature significantly affects the heat and mass transport in frozen soil. The phase change-induced variations in unfrozen water content with temperature variation in frozen soils can cause frost heave and thaw settlement, consequently compromising the stability of infrastructure. The typical soil frozen characteristic curve (SFCC) depicts the variation of unfrozen water content at different temperatures; however, the lack of a universal computational method for ascertaining model parameters, which primarily depend on empirical fitting, considerably undermines the model's computational efficiency. To solve the problem, premelting theory and probabilistic ice formation were used to calculate the parameters in SFCC model. Based on the SFCC model presented by the Van Genuchten model, the relationship among model parameters n and alpha and temperature, equivalent particle size, Hamaker constant and other physical quantities was derived. By verifying the experimental data of 10 groups of different soil samples, the proposed parameter calculation method can effectively predict the unfrozen water content, and the calculated values are in good agreement with the experimental values. The results show that the parameters in classical SFCC model are correlated with ice-water interface free energy, the density of liquid solution, density of ice, Hamaker constant equivalent particle size, latent heat and temperature. The parameter calculation method proposed in this study addresses the limitation of existing empirical models that they cannot derive parameter values directly without compromising the original model's predictive accuracy, thereby offering a new approach for utilizing the SFCC model to predict unfrozen water content and conduct multi-physics coupling numerical simulations.

Climate warming and human activities have exacerbated permafrost degradation, leading to thawing and subsidence. Ventilated embankments can effectively mitigate permafrost degradation. In snowy permafrost regions, snow frequently clogs ducts, thereby reducing cooling efficiency. This study proposes a new ventilated embankment, develops a numerical model incorporating duct resistance for enhanced precision, and evaluates both the effects of duct configuration on ventilation efficiency and the long-term thermal stability of normal versus new embankments in snowy permafrost regions of the Siberian Arctic (SA) and Qinghai-Tibetan Plateau (QTP). The new ventilated embankment improves heat transfer efficiency and reduces net heat transfer into the lower embankment. This design mitigates the differential impacts between sunny and shady slopes, reducing permafrost degradation by over 89%, thereby protecting underlying permafrost and enhancing embankment thermal stability. In the Siberian Arctic (SA) regions, the ventilated embankment demonstrates superior cold-season cooling efficiency and higher freezing degree-day accumulation compared to the Qinghai-Tibetan Plateau (QTP) regions, indicating greater suitability for SA. Analysis of the duct structural parameters shows that increasing duct diameter and lowering duct installation height significantly enhance cooling performance, while elevating the air inlet height yields only a minor change in effectiveness. The study's findings provide a scientific basis for the design and application of ventilated embankments in snowy permafrost regions.

The crushed-rock layer embankment (CRLE) has been widely used in road/railway construction in permafrost regions to maintain subgrade stability via natural convective heat transfer. However, its cooling capacity tends to degrade over time due to sand infilling, rock weathering, and climate warming, making it necessary to enhance the convection process in a non-excavation manner for in-service CRLEs. This study proposes a novel nonexcavation reinforcement method by inserting thermosyphons into the upper part of the embankment, and laboratory model tests were conducted to investigate the underlying enhancement mechanism. Under identical testing conditions, comparative experiments involving a conventional CRLE and a thermosyphon-enhanced CRLE were carried out over four freeze-thaw cycles. Based on monitored temperature, air velocity, and heat flux data, the following key findings were obtained: the thermosyphon achieved a peak heat drainage flux of -90.79 W/m2 and a net heat drainage of 27.53 MJ/m2 per cycle; it reduced the temperature at the crushed-rock layer (CRL) surface by up to 7.29 degrees C, thereby increasing the temperature difference across the CRL and enhancing the natural convection driving force, which resulted in a 42% increase in the maximum porous air velocity and a 19.2% extension of the natural convection active duration. In addition, the thermosyphon not only intensified the cooling magnitude of the CRL but also expanded the cooling area toward the central part of the embankment, increasing the heat released from the underlying soil during cold periods by 96.5% on average. The results validate that thermosyphon insertion is an effective non-excavation technique to actively enhance the cooling performance of in-service CRLEs, offering a rapid and low-impact solution for ensuring the long-term stability of transportation infrastructure built on permafrost.

Freeze-thaw cycles induce frost heave, thaw settlement, and long-term deformation in cold-region subgrades. This study investigatesd the coupled temperature, moisture, heat flux, and deformation responses of silty clay subgrades modified with sisal fiber (SF) and municipal solid waste incineration bottom ash (MSWIBA) under different pavement surface conditions. Four model subgrades were designed, i.e., untreated silty clay without surfacing, SF-MSWIBA-modified silty clay without surfacing, SF-MSWIBA-modified silty clay with a gravel surface, and SF-MSWIBA-modified silty clay with a concrete surface. Five freeze–thaw cycles were applied. The results showed that SF-MSWIBA modification reduced cumulative deformation from 5.83 mm to 4.22 mm at the end of the fifth freeze–thaw cycle, corresponding to a reduction of approximately 28%. Pavement surface conditions further regulated heat transfer, freezing depth, water redistribution, and deformation accumulation. The gravel surface produced the smallest cumulative deformation (1.12 mm), mainly because of its drainage-favorable structure. In contrast, the concrete slab strengthened thermal coupling with the ambient boundary, and reached a maximum freezing depth of 90 cm, while limiting surface deformation through mechanical constraint. These findings indicate that combining SF-MSWIBA modification with an appropriate pavement surface can improve the freeze–thaw resistance of cold-region subgrades.

In cold regions, repeated freeze–thaw disturbances can weaken saline soils and compromise long-term infrastructure performance, highlighting the need for durable, low-carbon-oriented stabilization. This research investigates the mechanical behavior and microstructural evolution of saline soils treated with a combined system of ionic soil stabilizer (ISS), lime, and fly ash, prepared under field-relevant compaction and subjected to controlled freeze-thaw conditions. Consolidated drained triaxial tests, mercury intrusion porosimetry, and scanning electron microscopy were performed to evaluate strength development and pore-structure evolution. The results show that the peak deviator stress increases progressively with freeze-thaw repetitions, increasing from 1707 to 2093 kPa before cycling to 2420–2502 kPa after 20 cycles under a confining pressure of 200 kPa, with the 9

In cold regions, traditional de-icing methods, including mechanical, chemical, and electrothermal techniques, are often associated with high costs and substantial operational demands. There is an urgent need to develop innovative de-icing technologies, particularly based on photothermal coating approaches. Therefore, this study developed Fe3O4 nanoparticle (NPs)-based photo-thermal coatings. The temperature response and de-icing effect of the coatings on concrete surfaces were systematically investigated through a series of experiments, including atomic force microscope (AFM) test, wettability test, UV-Visible-Near Infrared Spectrophotometer (UV-VIS-NIR) test, outdoor temperature response test, indoor temperature response and de-icing performance test, as well as freeze-thaw durability test. In addition, a preliminary cost-benefit analysis was performed to evaluate the economic feasibility of the Fe3O4 NPs-based photothermal coating. The results indicated that the surface roughness of the photothermal coatings significantly increased with increasing Fe3O4 NPs, thereby enhancing the microstructural integrity and surface morphology of the coatings. The increased nanoscale roughness of the coating led to a higher water contact angle and a lower sliding angle, which reduced water spreading and droplet adhesion and thereby promoting rapid meltwater removal during photothermal de-icing. Furthermore, the Fe3O4 NP-based photothermal coatings exhibited strong light absorption capability, particularly in the near-infrared region. The Fe3O4 NPs-15 coating exhibited the most pronounced photothermal response in terms of energy absorption, thermal storage, and de-icing performance. The coating also effectively mitigated freezing expansion pressure, thereby enhancing the freeze-thaw resistance of concrete. Moreover, the Fe3O4 NPs-based photothermal coating demonstrated a reasonable cost structure and promising economic potential. When compared with conventional de-icing methods, the proposed coating demonstrated lower longterm costs and superior de-icing efficiency. This study enhances the understanding of the temperature response and de-icing behavior of photothermal coatings on concrete surfaces in cold regions, and provides a promising strategy for effective de-icing in cold-region environments.

Soil thermal conductivity (STC), which plays an important role in the analysis of soil heat transfer, is widely used in various fields. In this study, based on the McKee and Bumb model for the soil-water characteristic curve (SWCC), a new STC calculation model is suggested to address the problem of insufficient prediction accuracy in existing STC models, and 27 Canadian soils are used to establish the new model. The new STC model is evaluated and compared with three existing models using six soils. For fine-grained soils over the full degree-of-saturation range, the results show that the new STC model achieves the highest prediction accuracy (RMSE = 0.056 W/mdegrees C), outperforming the Johansen model (RMSE = 0.077 W/mdegrees C), the Cot & eacute; and Konrad model (RMSE = 0.082 W/mdegrees C), and the Bi et al. model (RMSE = 0.062 W/mdegrees C). Furthermore, the prediction accuracy of the four models is discussed in stages, and the new STC model performs better in the degree-of-saturation (Sr) range of 0.1-0.8. Based on this, a segment calculation method combining the advantages of the four models is proposed. The segment calculation method can better simulate the variation of STC with Sr. It is established that the new model and the segment calculation method can improve the accuracy of predicting STC and can be used in numerical simulations to calculate STC (RMSE = 0.053 W/mdegrees C). The research results provide more reliable technical support for the analysis of STC of infrastructure in cold regions.

In cold regions, freeze-thaw cycles (FTCs) significantly affect the mechanical properties and microstructure of concrete, shortening service life and increasing maintenance costs. To mitigate this challenge, this study developed a high-thermal conductivity expanded graphite-based binary composite low-temperature phase change material (EG-BPCM). A macro-micro evidence chain was established to correlate phase change behavior with freeze-thaw damage and pore structure evolution. This phase change material (PCM), composed of n-tetradecane (C14) and n-octanoic acid (C8) impregnated into expanded graphite (EG), was incorporated into concrete as a functional admixture. Phase change concrete (PCC) mixtures with varying dosages of EG-BPCM, ranging from 0% to 5% by cement mass designated PCC-0 to PCC-5, were subjected to 200 rapid FTCs. The macroscopic and microscopic characteristics of the PCC exposed to specific FTCs were then evaluated. Differential scanning calorimetry (DSC) revealed that EG-BPCM exhibited a concentrated phase transition between -6 degrees C and 5 degrees C, with a characteristic phase change temperature of approximately 0.8 degrees C. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) confirmed the excellent chemical compatibility of EG-BPCM. Furthermore, compared to the controlled sample (PCC-0), the incorporation of EG-BPCM reduced concrete surface scaling, mass loss, and porosity after 200 FTCs. However, a non-monotonic trend and compromised compressive strength and dynamic modulus were observed. Notably, after 200 FTCs, PCC-3 exhibited a mass loss of 1.10% and a strength loss of 18.61%, with a relative dynamic elastic modulus retention of 81.2%. These results significantly outperformed PCC-0, which recorded values of 2.30%, 43.12%, and 50%, respectively. Moreover, water absorption, scanning electron microscopy (SEM) and low-field nuclear magnetic resonance (LF NMR) analyses indicated that PCC-3 possessed the lowest porosity (6.94%), dominated by approximately 85% harmless pores. Based on a comprehensive evaluation of freeze-thaw durability, mechanical degradation, and pore structure evolution, PCC-3 demonstrated the most balanced performance and was identified as the optimal dosage. EG-BPCM is an effective and chemically stable function material for improving the freeze-thaw durability of concrete, offering a practical solution for infrastructure in cold regions through thermal buffering and porescale stress mitigation.

Heat transfer in multiphase porous media during freezing is a fundamental issue in cold-region soil thermophysics. Motivated by thermal-risk assessment and remediation design at contaminated sites in cold regions, this study focuses on petroleum-contaminated soil (PCS), analyzes the main controlling factors and mechanisms of thermal conductivity during the freezing process and proposes a physics-based model for subzero prediction. Laboratory measurements were performed by over a temperature range between 20 and -20 degrees C, water contents of 8% to 20%, petroleum contents of 0% to 12%, and dry densities of 1.5-1.8 g & centerdot;cm(-3). Results show that thermal conductivity increases with water content and dry density, while exhibiting a non-monotonic response on petroleum content, initially decreasing at low contamination levels and subsequently increasing with a transition near similar to 8%. With decreasing temperature, thermal conductivity displays three states: a mild change above 0 degrees C, a sharp increase across the freezing interval due to ice formation and restructuring of conductive pathways, and a slight post-freezing decline consistent with contact degradation and possible freezing-driven petroleum redistribution. A solid-state series-parallel model was proposed, which explicitly incorporates the petroleum location coefficient and frost-heave effect. Validation against subzero experimental data demonstrates strong agreement (overall R & sup2; =0.805, MAE =0.072 W & centerdot;m(-)& sup1;& centerdot;K-& sup1;, RMSE =0.121 W & centerdot;m(-)& sup1;& centerdot;K-& sup1;). These findings provide important technical and theoretical support for the development of petroleum resources and the assessment and remediation of contaminated soils in cold regions.

Red-bed soft rock is a reddish-toned clastic sedimentary rock, which is widely distributed in southwest China. Quick and effective estimation of its strength can provide technical support for preliminary engineering design or less critical structure design in red-bed soft rock areas. Due to the low strength and easy disintegration and fragmentation of the red-bed soft rocks in southwest China, it’s difficult to prepare and transport standard cores in the field. In order to quickly obtain the strength index of red-bed soft rocks in southwest China, a series of laboratory index tests (Uniaxial Compression tests (UCT); Point Load tests (PLT); ultrasonic pulse velocity test (UPV); Schmidt rebound hammer test (SHR)) were performed. Regression analysis was conducted for each index to establish its corresponding prediction model. Validity analysis and a comparative study of the prediction models were carried out to assess the potential relevance of the strength properties of red-bed soft rocks and the accuracy of the prediction models. The results of the study show that within the 95

Two-phase closed thermosyphons (TPCTs) are widely used across permafrost infrastructure to cool the underlying frozen ground. Their performance is affected by the evaporator-to-condenser length ratio (LR). Yet, the mechanisms by which LR affects internal heat transfer processes in TPCTs remain unclear. This study develops a computational fluid dynamics (CFD) model to simulate two-phase flow and phase-change heat transfer within TPCTs at various LRs. Results indicate that under typical permafrost operating conditions, a small LR (e.g., 1.0) provides insufficient evaporative surface area, which results in an undeveloped vapor core. Increasing LR from 1.0 to 1.5 enlarges the high-temperature vapor core, intensifies phase-change activity, and decreases the thermal resistance by about 20.8%. For LRs between 1.5 and 1.75, thermal resistance varies by less than 0.01 K/W. This marginal variation shows that evaporative heat absorption and condenser heat rejection balance each other in this range. The condenser sustains an average heat-flux density of at least 25 W/m2. Beyond 1.75, vapor-phase transport resistance and decreased condensation efficiency lead to heat accumulation, raise thermal resistance and reduce heat transfer efficiency. These findings identify an optimal LR that promotes uniform temperature distribution and maximizes heat transfer efficiency, which mitigates permafrost thawing and extends infrastructure service life.

High-temperature crude oil in buried pipelines can warm the surrounding permafrost, thereby impacting the stability of pipelines in permafrost regions. Wax deposition caused by cooling crude oil may block pipelines, while enhancing thermal resistance to reduce heat transfer to permafrost. To clarify the impact of wax deposition on permafrost thermal stability, a coupled 'oil-wax-pipe-soil' heat transfer model was developed to analyze heat exchange between hot crude oil pipelines and permafrost. The results show that after 30 years, the maximum thaw depth of frozen soil is 8.05 m with thawing rate of 0.188 m/a when wax deposition is not considered, and 7.40 m with thawing rate of 0.166 m/a when a 10 mm wax layer is considered. Considering wax deposition, the maximum thaw depth is reduced by 0.52 m in cold season and 0.67 m in warm season, while the maximum lateral impact decreases by 0.59 m and the soil temperature at 4 m depth decreases by 0.6 degrees C. For wax thicknesses of 1 mm, 3 mm, 5 mm, and 10 mm, the maximum thaw depth decreases by 0.12 m, 0.25 m, 0.39 m, and 0.65 m, respectively. This study quantitatively characterizes the insulating effects of wax deposition in permafrost pipelines, providing critical guidance for thermal management in permafrost regions.

To embrace sustainable and environmentally friendly practices, sisal fibers have emerged as a green and low-carbon alternative, offering a viable approach for enhancing the physical characteristics of frost-vulnerable soils. In this study, the unconfined compressive strength and freeze-thaw cycle (FTC) tests for soils stabilized with sisal fiber were conducted, and the enhancement mechanism of sisal fibers on soils in cold regions was analyzed. The results showed that as the sisal fiber content raised, the unconfined compressive strength of the soil samples initially increased and then decreased, which reached a peak at 0.9% sisal fiber content. The heat flux in the sisal fiber-reinforced soil samples exhibited a more dramatic variation than that in the soils without adding fibers during the water-ice phase transition stage. The unfrozen water hysteresis in the fiber-reinforced soil samples initially decreased and then increased as the soil temperature decreased. With an increase in the FTCs, the frost heave for sisal fiber-reinforced soil samples occurred, whereas settlement appeared in the soils without adding fibers. The cumulative deformation of sisal fiber-reinforced soil samples was lower than that of the soils without adding fibers. Additionally, the thaw settlement rate was lower than that of frost heave rate for sisal fiber-reinforced soil samples, while the reverse results were occurred for the soils without adding fibers. The addition of sisal fibers established a more robust structural integrity to the soils.

The soil above the water table in the shallow layers of the Earth is typically unsaturated, and understanding the complicated multiphase contact modes and interactions in unsaturated is crucial for accurately simulating multi‐physical field coupling and predicting foundation deformation in frozen soil region. In this study, a theoretical model for unfrozen water content in unsaturated soils by integrating the generalized interface premelting theory with Gibbs free energy minimization. The model resolves the phase transition processes at the interfaces of air‐water‐ice‐soil by determining air‐phase distribution within pore spaces and incorporating interfacial melting effects at air‐ice and soil‐ice boundaries. Additionally, we incorporated the concept of effective water content to improve calculation accuracy, and the model was validated using experimental data. The results indicate that the equilibrium contact angle between air and soil particles is primarily influenced by air saturation and is independent of soil pore size. As air saturation increases, the equilibrium contact angle and the radius of the ice‐water curvature interface enlarges, the melting effect between soil particles and ice crystals diminishes, and the unfrozen water content decreases. In addition, soils with smaller pore sizes and lower saturation exhibit higher surface free energy, which inhibits ice nucleation. Consequently, the soil freezing characteristic curve (SFCC) of silty clay demonstrates significant sensitivity to air saturation, unlike coarse‐grained soils (e.g., silt, sand), where air saturation minimally influences the SFCC. These results advance predictive frameworks for hydrothermal behavior in unsaturated frozen soils, particularly in fine‐grained geomaterials.

The phase transition characteristics of saline soil are closely related to its electrochemical processes. It is an effective means to investigate the phase transition mechanism by using the electrochemical characteristics of saline soil. In order to explore the electrochemical characteristics of composite saline soil in phase transition process, the electrochemical impedance spectrum of saline soils with different mass ratios of chloride and sulfate ions were tested through cooling tests. The results reveal that Nyquist plots exhibit a single reactance arc at positive temperatures, and the water/salt migration in the soil changes the electrochemical reaction process after the pore water freezing, resulting in the appearance of diffusion impedance. The impedance modulus increases linearly with the decrease in temperature before phase transition, while the formation of salt crystals and ice crystals leads to a significant increase in the impedance modulus after phase transition. The phase angle is close to zero degrees at a scanning frequency of 105 Hz, indicating that the soil system exhibits resistive behavior. Moreover, the equivalent circuit model is established according to the conductive path of the composite saline soil. It was found that there is a close correlation between the value of equivalent resistance elements and the impedance modulus through comparison. In addition, the machine learning algorithms were used to predict the variation of equivalent resistance elements, which demonstrate that the XGBoost model can effectively predict the variation of resistance value, with an R2 of 0.995. This research provides a theoretical reference for studying the salt expansion and frost heave mechanism of saline soil in cold regions.

To study the effect of increased rainfall on the heat and mass transfer and deformation characteristics of sulfate saline soil, a geometric similarity ratio model (1:6) of the natural site was created inside the self-developed indoor baseplate-atmospheric dual-temperature control model box. For the first time, combined with the characteristics of the surface energy change, the characteristics of water-heat-salt-mechanical coupling changes within sulfate saline soil under normal rainfall and twice the increase in rainfall were studied. The results show that the increased rainfall leads to a more significant decrease in upward shortwave radiation and downward longwave radiation, as well as a more significant increase in the surface net radiation and surface evaporation rate. Additionally, the increase in rainfall leads to an obvious cooling trend in the surface temperature. Compared with normal rainfall, an increase in rainfall leads to a significant increase in soil water content and conductivity, while soil heat flux and temperature significantly decrease. The increased rainfall caused a temperature drop of 1.6 degrees C at 5 cm of saline soil. Moreover, the increased rainfall leads to an increase in the heat release time of sulfate saline soil. Meanwhile, the impact of increased rainfall on the soil water content, conductivity, and temperature gradually weakens with increasing depth. The increased rainfall can exacerbate thawing settlement deformation and alleviate salt frost heave deformation. Compared with normal rainfall, twice the increase in rainfall results in a 0.9 mm increase in thawing settlement deformation and a 2.5 mm decrease in salt frost heave deformation.

The development and exploitation of petroleum resources in cold regions have exacerbated the risk of petroleum spills, which can adversely affect the safety of infrastructure, particularly under freeze-thaw cycles. This study investigates the impact of freeze-thaw cycles on the shear strength of petroleum-contaminated soil. Direct shear tests are conducted on soil samples with varying water content, petroleum contamination levels, and freeze-thaw cycles. The results reveal that an increase in water content leads to a reduction in the shear strength of petroleum-contaminated soil. Furthermore, higher petroleum content fills the pore spaces of the soil, weakening its shear strength by diminishing both cohesion and internal friction. The freeze-thaw cycle further decreases soil shear strength, with a more pronounced effect at higher petroleum contents. Specifically, the shear strength undergoes a sharp decline after the first freeze-thaw cycle and stabilizes with subsequent cycles. Scanning electron microscopy observations postshear testing show that petroleum reduces interparticle cohesion, while freeze-thaw cycling induces particle size homogenization, both of which contribute to the decrease in shear strength. A Mohr-Coulomb-based shear strength model, incorporating water content, petroleum contamination, and freeze-thaw cycles, is developed and validated. The model demonstrates strong predictive accuracy, with a high correlation coefficient (R-2 = 0.968) between predicted and measured shear strength values, providing valuable insights for assessing the safety of structures in petroleum-contaminated sites in cold regions.