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Composite geotextiles are frequently utilized in water delivery canals and other projects in cold regions. However, the peak strength of the soil-geotextile interface can be degrade due to continuous wet-dry-freeze-thaw (WDFT) cycles, potentially compromising the stability of the infrastructure. This paper presents the use of a temperature-controlled direct shear system to conduct direct shear tests on the interface between the soil and the geotextile composite under a variety of normal pressures, temperatures, and WDFT cycles. The study shows that WDFT has minimal effect on the shear stress-shear displacement curve at positive temperatures. At negative temperatures, the curve transitions from strain hardening to strain softening. At negative temperatures, the average increase in peak strength was 39 %, 56.9 %, and 65.3 % after a single WDFT cycle at −2 °C, −6 °C, and −10 °C, respectively. A gradual decline in peak strength was observed with each subsequent cycle, although the peak strength remained slightly higher than the initial strength. The average growth rates were 6.6 %, 19.3 %, and 29.2 % after ten cycles, respectively. The interfacial cohesion and friction angle exhibited similar trends to those of peak strength. The sensitivity analysis revealed that temperature and WDFT cycles exert a considerable influence on the interface cohesion.

Buried pipelines have been widely used to transport petroleum-based products over long distances in permafrost regions. Field observations reveal that they are endangered by rapid permafrost thawing and resulting massive soil movements, despite adopting some measures to protect pipeline foundation permafrost. A new mitigation technique is proposed to slow down the permafrost thawing ulteriorly. With this technique, a seasonal air-cooled embankment (SACE), mainly composed of a crushed rock layer, supports the pipeline and transfers the heat from the pipeline to ambient air in the cold seasons. A scale model test with the controlled air and oil temperatures was carried out to evaluate the proposed measure. The temperature and volumetric unfrozen water content of the permafrost subgrade beneath both the SACE and the direct-buried pipeline, as well as ground surface displacements, were measured during the whole testing process. A comparison of the hydrothermal process of the subgrade permafrost under the SACE and the direct-buried warm pipeline indicates that the proposed measure can substantially mitigate the rapid thawing of permafrost by controlling the geothermal regimes of the pipeline.

Soil properties play a crucial role in the stability of engineering foundations, particularly in cold regions where temperature gradients impact water migration and soil conditions. This study utilized MRI-Cryogenic Soil-Moisture Analyzer (MRI-CSMA) to conduct indoor freeze-thaw experiments on silty clay specimens with varying initial water contents (12.0 %, 16.8 %, and 21.1 %). Dynamic changes in water content and temperature at different soil depths were analyzed. The results revealed distinct stage decrease characteristics in both temperature and water content as freezing progressed, with more pronounced changes closer to the cold end. Conversely, during thawing, temperatures and water content gradually increased as the boundary temperature rose. Notably, after the freeze-thaw cycle, the frozen zone consistently retained higher water content than the unfrozen zone, indicating water redistribution, regardless of initial water content levels. Furthermore, in three soil samples with different initial water contents, the water migration flux in the unfrozen soil layer decreased exponentially as freezing time increased. This phenomenon can be attributed to the combined effects of water boundary conditions, temperature gradients, and soil structure changes during soil freezing. These findings are likely to have significant implications for understanding water-heat dynamics in cold region soils as well as ensuring the stability of engineering projects.

The shear characteristics of the soil-geosynthetic interface are the primary factors affecting the load transmission rules. The interfacial shear parameters are affected by cycles of freeze-thaw and alter as a result of the periodic temperature fluctuations. Using an enhanced temperature-controlled direct shear apparatus, this paper investigates the interfacial shear characteristics between silty clay and composite geotextile according to freeze-thaw cycles. Analysis is done on how the interfacial stress-strain relationship, strength, and strength characteristics are affected by the soil moisture content, normal pressure, and test temperature. The results demonstrate that at low freezing temperatures and high moisture contents, the interfacial stress-strain curve is strongly influenced by cycles of freeze-thaw, and that the interfacial shear strength tends to grow initially before decreasing as the number of freeze-thaw cycles increases. The variations in interfacial shear strength correlate to the changes in interfacial friction angle and interfacial cohesion, and the primary element influencing the variation of shear strength is the alteration in interfacial cohesion. With a high soil moisture content initially, the migrating water has greater effect on shear strength during the freeze-thaw cycle. The findings of the significant level research indicate that the moisture content has a significant influence on the shear strength.