In this paper, through extensive on-site research of the plain concrete composite foundation for the Jiuma Expressway, the study conducted proportional scaling tests. This study focused on the temperature, moisture, pile-soil stress, and deformation of this foundation under freeze-thaw conditions. The findings indicate that the temperature of the plain concrete pile composite foundation fluctuates sinusoidally with atmospheric temperature changes. As the depth increases, both temperature and lag time increase, while the fluctuation range decreases. Furthermore, the effect of atmospheric temperature on the shoulder and slope foot is more significant than on the interior of the road. During the freeze-thaw cycle, the water content and pore-water pressure in the foundation fluctuate periodically. The pile-soil stress fluctuates periodically with the freeze-thaw cycle, with the shoulder position exhibiting the most significant changes. Finally, the road displays pronounced freeze-thaw deformations at the side ditch and slope toe. This study provides a valuable basis for the construction of highway projects in cold regions.

High-strength mortar (HSM) gradually has wide applications due to its exceptional strength, micro-expansion properties, and excellent fluidity. Behavior deterioration of structures in saline soil areas is primarily attributed to freeze-thaw cycles and sulfate attack. In this study, the coupling effect of freeze-thaw cycles and sulfate attack on the appearance, mass loss, and relative dynamic elastic modulus of HSM was investigated during erosion. Then, compressive experiments were conducted to assess the mechanical properties of HSM subjected to both freeze-thaw cycles and sulfate attack. The influences of coupling freeze-thaw cycles and sulfate attack on the compressive properties of HSM were quantified through regression analysis of experimental results. Empirical models for compressive stress-strain curves and damage constitutive behavior of HSM were developed, taking the coupled adverse effect into account. The results indicate that the coupled effect of freeze-thaw cycles and sulfate attack causes performance deterioration of HSM. The empirical models reproduce the compressive behaviors of HSM subjected to freeze-thaw cycles and sulfate attack.

Volume changes in soil caused by freeze-thaw cycles can affect the shear performance of the saline soil-geotextile interface. To investigate this issue, the study examined changes in shear strength, deformation characteristics, and failure modes of the saline soil-geotextile interface under different numbers of freeze-thaw cycles. The experimental results indicate that with the increase in freeze-thaw cycles, the shear stiffness of the interface initially increases and then decreases, demonstrating the reduction in elasticity and resistance to deformation caused by freeze-thaw cycles. And the enhancement of normal stress can effectively increase the density of the soil and the adhesion at the interface, thereby improving shear stiffness. Meanwhile, the salt content in the soil also significantly impacts the mechanical properties, with notable changes in the dynamic characteristics of the interface as the salt content varies. Furthermore, after freeze-thaw actions, the soil becomes loose, reduces in integrity, features uneven surfaces, and sees increased internal porosity leading to slip surfaces. Trend analysis from this study provides new insights into the failure mechanisms at the saline soil-geotextile interface.

The stability of soil in high-altitude regions is significantly affected by freeze-thaw cycles, which alter its mechanical and physical properties. This study investigates the impact of 12 consecutive freeze-thaw cycles on poorly graded sandy-silt soil collected from Arunachal Pradesh. To enhance soil resistance, a bio-slurry containing urea (60 g/L) and calcium chloride (111 g/L), along with vetiver and bamboo fibers (by soil weight), was introduced as a stabilizing agent. The durability of the treated soil was evaluated by measuring the weight fluctuations after each cycle and assessing unconfined compressive strength (UCS) after 5, 10, and 12 cycles. The results revealed that untreated soil experienced a 50% reduction in UCS, while bioslurry-treated soil retained 70-80% of its original strength after 12 freeze-thaw cycles. The greatest strength retention was observed in soil treated with bioslurry and bamboo fiber, which retained 80% of its strength, followed by vetiver-treated soil at 75% strength retention. Weight loss measurements indicated that untreated soil samples lost 9.5% of their initial mass, whereas bioslurry-treated samples exhibited only a 3-5% weight loss. The findings of the study highlight the potential of bioslurry and natural fibers in mitigating freeze-thaw-induced soil degradation, making them suitable for applications in geotechnical engineering in cold-climate regions.

Geopolymers are recently recognized as superior sustainable alkali-activated materials (AAMs) for soil stabilization because of their strong bonding capabilities. However, the influence of freeze-thaw cycles (FTCs) on the performance of geopolymer-stabilized soils reinforced with fibers remains largely unexplored. In the current study, for the first time, the durability of polypropylene fiber (PPF) reinforced clayey soil stabilized with fly ash (FA) based geopolymer is investigated under FTCs, evaluating its performance during prolonged seasonal freezing. The effects of repeated FTCs (0, 1, 3, 6, and 12 cycles), different contents of alkali-activated FA (5 %, 10 %, and 15 %), varying PPF percentages (0 %, 0.4 %, 0.8 %, and 1.2 % with a length of 6 mm), and curing time (7 and 28 days) on the properties of stabilized samples have been determined through tests including standard Proctor compaction, unconfined compressive strength (UCS), mass loss, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR). The results revealed that a 0.4 % PPF concentration maximized strength in FA-based geopolymer samples by restricting crack propagation, irrespective of FA content, number of FTCs, or curing time. However, higher PPF contents lowered UCS values and Young's modulus due to fiber clustering and increased failure strain, respectively. Generally, an initial increase in UCS, Young's modulus, and resilience modulus (MR) of stabilized samples occurred with more FTCs because of their dense structure, delayed pore formation, and continued geopolymerization process and followed by a constant or decreasing trend in strength after 6 (or 3 in some cases) FTCs due to ice expansion in created air voids. Longer curing time resulted in denser samples with improved resistance to FTCs, especially under 12 FTCs. Moreover, samples with 10 % alkali-activated FA demonstrated the least susceptibility to FTCs. While initial FTCs caused no mass loss, subsequent cycles led to increased mass loss and remained below 2 % for all samples. Microstructural analysis results corroborated UCS test results. Although the primary chemical composition remained unchanged after 12 FTCs, these cycles induced morphological changes such as critical void formation and cracking within the gel structure. The stabilization approach proposed in this study demonstrated sustained UCS after 12 FTCs, promising reduced maintenance costs and extended service life in regions with prevalent freeze-thaw damage.

The fundamental cause of frost heave and salt expansion of saline soil is the water condensation and salt crystallization during the freezing process. Therefore, controlling the water and salt content is crucial to inhibit the expansion behaviors of saline soil. Recently, electroosmosis has been demonstrated to accelerate soil dewatering by driving hydrated cations. However, its efficiency in mitigating the salt-induced freezing damages of saline soil requires further improvement. In this study, a series of comparative experiments were conducted to investigate the synergistic effects of electroosmosis and calcium chloride (CaCl2) on inhibiting the deformation of sodium sulfate saline soil. The results demonstrated that electroosmosis combined with CaCl2 dramatically increased the cumulative drainage volume by improving soil conductivity. Under the external electric field, excess Na+ and SO42- ions migrated towards the cathode and anode, respectively, with a portion being removed from the soil via electroosmotic flow. These processes collectively contributed to a significant reduction in the crystallization-induced deformation of saline soil. Additionally, abundant Ca2+ ions migrated to cathode under the electric force and reacted with OH- ions or soluble silicate to form cementing substances, significantly improving the mechanical strength and freeze-thaw resistance of the soil. Among all electrochemical treatment groups, the soil sample treated with 10 % CaCl2 exhibited optimal performance, with a 71 % increase in drainage volume, a 180 similar to 443 % enhancement in shear strength, and a 65.1 % reduction in freezing deformation. However, excessive addition of CaCl2 resulted in the degradation of soil strength, microstructure, and freeze-thaw resistance.

Freeze-thaw (FT) cycles significantly affect soil permeability and could cause geological and environmental disasters. This study investigated the influence of FT cycles on the permeability of compacted clay through triaxial permeability tests, considering freezing temperature, cycle number, water content, and confining pressure. Scanning electron microscopy and nuclear magnetic resonance tests were performed to analyze the microstructure and pore characteristics of the clay during FT cycles. The results show that the hydraulic conductivity of the clay decreases significantly at high confining pressures due to soil consolidation. When the confining pressure exceeds 150 kPa, the impact of FT cycles on hydraulic conductivity becomes negligible. The increased number of FT cycles, exposure to lower freezing temperatures, and higher water content lead to more pronounced soil structure damage, resulting in a substantial increase in hydraulic conductivity. FT cycles cause macropores and microcracks to form and increase the average pore radius, creating preferential seepage pathways. Correlation analysis indicates that the increase in macropore content under various FT cycles is the primary reason for the increased hydraulic conductivity. Based on the modified Kozeny-Carman equation, a prediction model is developed to effectively estimate the hydraulic conductivity. These results provide valuable insight into the damage mechanism of clay permeability in seasonally frozen regions from a microscale perspective.

In cold regions' engineering applications, cement stabilized soils are susceptible to strength degradation under freeze-thaw (F-T) cycles, posing significant challenges to infrastructure durability. While metakaolin (MK) modification has shown potential in enhancing static mechanical properties, its dynamic response under simultaneous F-T cycling and impact loading remains poorly understood. This study investigates the dynamic mechanical behavior of cement-MK stabilized soil through split Hopkinson pressure bar (SHPB) tests under varying F-T cycles. The effects of strain rate and F-T cycles on the dynamic failure process and mechanical properties of cement-MK stabilized soil were investigated. Pore characteristics were analyzed using a nuclear magnetic resonance (NMR) system, providing an experimental basis for revealing the degradation mechanism of F-T cycles on the strength of cement-MK stabilized soil. Based on the Lemaitre's strain equivalence principle, a composite damage variable was derived to comprehensively characterize the coupled effects of F-T cycles and strain rate. A dynamic constitutive model is established based on damage mechanics theory and the Z-W-T model. The results indicate that under the effect of F-T cycles induce progressive porosity increase and aggravated specimen damage. At varying strain rates, the strength of cement-MK stabilized soil decreases with increasing F-T cycles, while the rate of strength reduction gradually diminishes. Under impact loading, both strain rate and the number of F-T cycles significantly reduce the average fragment size of fractured specimens. The modified Z-W-T model effectively predicts the stress-strain relationship of the cement-MK stabilized soil under impact loading.

Frozen-soils with different moisture contents (MCs) often experience freeze-thaw cycles (FTCs) owing to fluctuations in seasonal or day-night temperature. The influence of FTC on the impact dynamic mechanical properties of frozen-soils with different MCs was investigated in this study. The impact dynamic compression tests on frozen-soils with different MCs (20%, 25%, and 30%) following varying numbers of FTC (0, 1, 3, 5, and 7) using a split Hopkinson pressure bar apparatus were conducted. The experimental results revealed that the impact dynamic strength of the frozen-soil was related to the number of FTC and MC. A threshold exists for the number of FTC for the frozen-soil. Before reaching this threshold, the impact dynamic strength of the frozen-soil progressively decreased with an increasing number of FTC. Further, the threshold decreased as the MC decreased. Analyzing the energy of frozen-soil during impact process, an expression for the FTC damage in frozen-soils with different MCs was established using the energy density. The reinforcing effect of ice particles on the impact dynamic mechanical properties of frozen-soil was examined, and the elastic constants for the frozen-soils with different MCs were evaluated using micromechanical theory. Furthermore, a finite element numerical model of frozen-soil was developed by integrating cohesive elements into solid elements via Python scripting using the cohesive zone model. The impact dynamic mechanical behavior and crack evolution behavior of frozen-soils with different MCs following varying numbers of FTCs were simulated by considering the mechanisms of FTC degradation and ice particles reinforcement. The validity of the model was confirmed by comparing simulation and experimental results.

In cold regions, and considering the increasing concerns regarding climate change, it is crucial to assess soil stabilisation techniques under adverse environmental conditions. The study addresses the challenge of forecasting geotechnical properties of lime-stabilised clayey soils subjected to freeze-thaw conditions. A model is proposed to accurately predict the unconfined compressive strength (UCS) of lime-stabilised clayey soils exposed to freeze-thaw cycles. As the prediction of UCS is essential in construction engineering, the use of the model is a viable early-phase alternative to time-consuming laboratory testing procedures. This research aims to propose a robust predictive model using readily accessible soil parameters. A comprehensive statistical model for predicting UCS was developed and validated using data sourced from the scientific literature. An extensive parametric analysis was conducted to assess the predictive performance of the developed model. The findings underscore the capability of statistical models to predict UCS of stabilised soils demonstrating their valuable contribution to this area of study.