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![Parameters q and r of typical species in UNIQUAC [16].](publication/343567847/figure/tbl1/AS:932538524639233@1599345918231/Parameters-q-and-r-of-typical-species-in-UNIQUAC-16_Q320.jpg)
Engineering practices illustrate that the water phase change in soil causes severe damage to roads, canals, airport runways and other buildings. The freezing point is an important indicator to judge whether the soil is frozen or not. Up to now, the influence of salt on the freezing point is still not well described. To resolve this problem, a serie...
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... The soil pore water usually freezes below that temperature which is primarily due soil grain matrix effects and osmotic effects (Wang et al. 2021). While matrix effect encompasses the effects of soil structure, fabric, grain size and pore size distribution (Kozlowski 2009;Wen et al. 2012;Wan & Yang 2020;Wan et al. 2021), the osmotic effect includes the effect of solutes in the pore water (Ming et al. 2020). Presence of solutes in soil pore water depresses the freezing point of soil and this depression is greater for lower water contents (Arenson & Sego 2006;Bing & Ma 2011). ...
... The soil remains at this temperature till the free pore water in the soil freezes. The soil temperature may drop even further subject to the ambient temperature of the soil (Ming et al. 2020). The freezing point of soil is lowered by the presence of solutes in soil pore water, and this depression is larger for lower water contents (Arenson & Sego 2006;Torrance & Schellekens 2006;Shah & Mir 2022). ...
... The addition of salt lowers the overall potential of soil water while lowering the molecular interactions. As the salt content rises, the water activity drops resulting in the drop in freezing point of the soil (Ming, et al., 2020). As the pore solution freezes, the formation and growth of ice crystals is associated with the rejection of solute molecules into the unfrozen water. ...
Frost geotechnics is an essential subfield within geotechnical engineering, focusing on the complex interactions between freezing temperatures and soil properties. Soil is said to be in a frozen state when its temperature falls below its freezing point and possess relatively high strength. However, an overlying structure may sustain damage because of issues caused by the alternate freezing and thawing of ground. The near-surface soil freeze/thaw state of the in-situ ground is related to the variation in temperature, which induces frost heave and frost thaw as the main geotechnical problems of frozen soils. In cold regions, these seasonally frozen soils are subjected to freezing thawing cycles and undergo significant volumetric changes, which have caused considerable damage to the structures such as road,
railroad, pipeline, and buildings built on, in or with them. Generally, the fine grained soils undergo significant impact of freezing-thawing cycles compared to coarse grained soil and show drastic changes in water content, volume, compressibility, strength, bearing capacity and microstrucrural arrangement of soil grains/particles during pre-and post freezing-thawing cycles. Therefore, this manuscript presents a comprehensive overview of the key concepts, challenges, and advancements in frost geotechnics. The manuscript explores the geotechnical consequences of frost
action, including frost heave, thaw weakening and changes in soil strength and stiffness due to thawing permafrost. The existing literature has been presented in the form of milestones. Further, this manuscript highlights the need for advanced modelling approaches, improved climate change impact assessments, and advanced monitoring systems to address the evolving challenges posed by freezing environments.
... Previous studies on theoretical coupling models of water-heat-mechanics and water-heatsalt-mechanics in freezing soil and the numerical solutions of these models determined that pore pressure is the main driving force for water migration in freezing soil (Lai et al., 2017;Zhang et al., 2020), and water-heat-salt-mechanics interact with each other (Tounsi et al., 2020). Moreover, the freezing point is related to the energy status of liquid water in saline soils and decreases with increasing salt concentrations, and the freezing point depression of saline soil is predominantly caused by a decrease in the water activity (Ming et al., 2020). Higher solution concentrations lead to easier precipitation of mirabilite at the same environmental temperature, and the freezing point of sodium sulfate in saline soil is lower than a sodium sulfate solution (Wan and Lai, 2013). ...
To date, most studies on coupled-water-and-heat processes in frozen soils haves focused on the mechanism of changes in frozen soil and the contribution of climate change, hydrological processes, and ecosystems in cold regions. Several studies have demonstrated considerable improvements in the accuracy of simulating water and heat transfer processes in cold regions. However, substantial differences remain among the different models and parameterizations because of the lack of observations and in-depth understanding of the water and heat transfer processes. Hence, it is necessary to summarize recent advances in the simulation of water-and-heat-coupling processes and challenges for further research. Therefore, we present a theory-focused summary of progress in this field considering the aspects of water flow and coupled-water-and-heat transfer. The simulation progress is discussed in terms of physical process models; one type of model only considers the heat conduction transfer processes without water flow, and the other considers coupled-water-and-heat transfer processes. Aspects of model deficiencies related to non-conductive heat transfer and soil water transfer processes in the frozen soil are also summarized. Moreover, the major parameterizations are reviewed, including phase changes, freeze-thaw fronts, thermal conductivity, hydraulic conductivity, snow processes, surface parameterization schemes, ground ice, and lower boundary conditions. While models and parameterizations can suitably capture local-scale water and heat transfer processes in frozen soil, their applications are spatiotemporally constrained, requiring further improvement. We provide a theoretical basis for further studying water and heat transfer processes in frozen soil and suggest that future research should enhance the accuracy of frozen soil parameterization and improve the understanding of the coupling of water and heat transfer processes based on improved observation techniques and high-resolution data.
... Due to alternate freeze thaw conditions, formation of cracks has been observed in stabilised soils that result in strength loss and excessive increase in hydraulic conductivity, thus destroying the whole purpose of stabilisation (Yıldız and Soğancı 2012;Bandara et al. 2015;Lu et al. 2020). It has been observed that the presence of salt in soil lowers the overall pore water potential while lowering the water activity resulting in the depression in freezing point of the soil (Ming et al. 2020). Decreased freezing point results in increased unfrozen water content during freezing. ...
Freeze–thaw experiments were conducted on a frost susceptible soil stabilised using alccofine and incorporating a soluble salt in pore water. The objective behind the investigation was to study the effect of solute incorporation on the frost susceptibility of alccofine-stabilised soil. The optimum alccofine content by weight of dry soil corresponding to maximum unconfined compressive strength of the treated soil was first determined. Then, alccofine-treated samples with and without 5% CaCl2 (salinity in pore water) were prepared for testing in a customised laboratory-based freeze–thaw test setup that allowed unidirectional freezing of the sample. The maximum frost heave, the heave rate, and the thaw-CBR were compared for different samples tested. In addition, the effects of salinity on depth of frost infiltration and moisture movement during freeze and thaw were also studied. By lowering the overall ice content during freezing, the existence of pore water salinity was found to alter the treated soil’s overall frost susceptibility by reducing frost heave, depth of frost infiltration, and moisture movement towards the freezing front and generating higher thaw-CBR compared to non-saline treated samples. Also, less soil degradation at the microstructural level was established by scanning electron micrographs.
... Beside hysteresis effect, it is found that the shape of SFCC depends also on several factors, including liquid limit [69], stress condition [50], salt content and solute types [48,76], initial water content or degree of saturation [34,65,80], types of soil [16,44,90], pore-size distribution [45], and fines content [45,68,69,90]. Among these factors, fines content can influence others (liquid limit, pore-size distribution and types of soil). ...
... Smaller specimens were used when measurements were performed by pulsed-NMR method [47,66,68]. In several previous works, specimens were immerged in a cooling bath with constant cooling rate or at low temperature (between -15 and -30°C) and kept for several hours [14,48,74,75]. For determining SFCC, unfrozen water content was measured at various controlled temperatures [34,47,54,57,80,90]. ...
... Numerous studies investigated T f and showed that T f depends on many factors such as salt content [11,13,25,48,75], salt types [14,74], initial water content [4], and soil types [18,39,42,45,66,90]. In the present study, T f was found close to 0°C for all soils. ...
Soil freezing characteristic curve (SFCC) represents the relationship between soil temperature and unfrozen water content of soil during freezing and thawing processes. In this study, SFCC of sandy soils was determined in laboratory. Pure sand was mixed with clay at various contents (0, 5, 10, 15, and 20% of the total dry mass), and the mixtures were compacted to their respective maximum dry density. Compacted specimens were then placed in a close and rigid cell, and the soil’s temperature was decreased step-by-step to freeze the soil water and then increased back to thaw it. During this thermal cycle, soil’s temperature and volumetric water content were monitored in order to determine the SFCC. The results show that SFCC was strongly dependent on the fines content: at higher fines content, the temperature of spontaneous nucleation was lower, and the residual unfrozen volumetric water content was higher.
... Soil usually freezes at a temperature lower than the freezing point of pure water which is due to the soil matrix effect and osmotic effect [25]. While matrix effect encompasses the effects of soil structure, fabric, grain size and pore size distribution [24], the osmotic effect includes the effect of solutes in the pore water [17]. Presence of solutes in soil pore water depresses the freezing point of soil and this depression is greater for lower water contents [2,6,20]. ...
The susceptibility of soil to frost action is a major distress for engineering infrastructure constructed over it in regions that experience seasonal freezing and thawing. The soil deposits which are not otherwise problematic for use as a subgrade/foundation material can become very problematic under seasonal freeze-thaw. Since presence of dissolved salts in pore water depresses the freezing-point and increases the unfrozen water content, it can be ascertained that pore water salinity can affect soil frost susceptibility due to seasonal temperature variations by reducing the total ice content during freezing. An experimental investigation was carried out to assess the effect of pore water solute content on the behaviour of a frost susceptible soil subjected to freeze-thaw cycles in a laboratory test setup as per ASTM D5918-13. The presence of solute primarily depressed the freezing point of the soil. The heave rate, maximum heave and the frost penetration depth was found to decrease with increasing solute concentration in pore water. The effect on the thaw-CBR value, variation in water migration pattern and micro-structural changes along the depth of the sample was also examined. It was found that the presence of solutes negates the undesirable effects during freezing by controlling ice segregation, frost penetration and heaving of the soil which in turn limit the adverse weakening during thawing. The destruction to soil at micro-structural level was also restricted in the samples containing solute in their pore water.
... FP has many practical applications in the realm of engineering and environment of frozen soils, e.g., artificial ground freezing technology, frozen heaving, thaw settlement, distinguishing salt expansion from frost heaving in saline soils in cold regions, oil transportation and spreading by the freeze-thaw action in oil-polluted soils (Grechishchev et al., 2001;Wan et al., 2015), and hydrothermal coupling simulation in the land surface model (Oh et al., 2020). An accurate estimation of soil water FP is practically essential; however, FP is always affected and depressed by many factors (Ming et al., 2020). Therefore, exploring the phenomenon of FP depression in soils remains a key issue. ...
... To overcome these limitations, formulas that consider both the surface curvature and interface effects were developed to further interpret the FP depression (Dash et al., 2006;Wettlaufer and Worster, 2006). When considering the solute, the FP depression can be derived using the electrolyte solution theory such as the UNIQUAC model (Ming et al., 2020), which is usually related to water activity. To date, no unified theory seems to explain all the empirical rules of FP depression alone, for it is difficult to characterise the pore water state (PWS) considering all the effects (Zhang et al., 2021). ...
The freezing point (FP) of soil water is a vital parameter for hydrothermal coupling simulations in cold regions, and is frequently depressed during soil freezing. Many studies have widely investigated the rules of FP depression affected by the soil type, water content, solute concentration, and external loading; however, few studies have clarified the underlying mechanisms. Water in soils is spatially non-uniform in nature, and the pore water state (PWS) (e.g., pressure) is essential to the FP depression. However, less attention has been paid to the FP depression considering spatially non-uniform nature of soil water. In this study, the FP depression was investigated considering the spatially varied pore water pressure (PWP) and non-uniform nature of soil water. The results showed that the FP depression depends on spatially increased PWP, and the Clausius-Clapeyron equation (CCE) for the phase transition of bulk water can be applied to soil water. These results were verified by two groups of typical experiments of FP with clay soil (external loading Pe = 0, 2, 4, 6, 8, and 10 MPa; gravimetric water content θ = 25, 30, 34, and 38%) and silty clay soil (salt concentration C = 0, 0.5, 1; gravimetric water content θ = 15, 20, 30, 40, and 50%). In addition, the PWP and its components were investigated using the proposed empirical formula.
... All the free pore water then freezes at this temperature, T f . The temperature then starts decreasing further depending on the ambient temperature [6,7]. ...
Determination of freezing point is the prerequisite for any laboratory or
field study on the freeze–thaw behaviour of soils. Depression in the freezing point
of soil pore water as compared to pure water (which freezes at 0 °C) in a two-phase
or a three-phase soil system is associated with several factors such as water content,
mineralogical composition, salinity of pore water, pore size, plasticity of soil, etc. An
experimental study was conducted on three types of soils of different plasticity and
gradation to study the effects of water content, salinity of pore water and plasticity
of soil on the freezing point depression. The results showed that the freezing point
significantly depresses only when water content decreases beyond a certain value.
The freezing point also showed depression with increasing soil plasticity and a linear
depression with increasing salinity of pore water. The study is a part of extensive
laboratory investigation on frost susceptibility of soils in Kashmir.
... Experimental results by Ming et al. [25] show that the freezing point is related to the energy status of liquid water in saline soils. The freezing point becomes lower the greater the salt concentration. ...
Open-pit mines can cause environmental changes, such as alterations of landscape structure, hydrology, air quality, and river sediments; they can also generate cones of depression. We propose a new method for surveys of mine waters using the example of an open-pit mine in central Poland. This study examines the correlations between bioluminescence and the color of brown coal mine waters and tests whether values of the three-color coordinate system reflected the physicochemical quality of mine waters measured in real-time and in the field. Our results show that alkalinity, pH reaction, and conductivity are higher in surface drainage, while values of trophic parameters (soluble reactive phosphates, total phosphorus, nitrates) are greater in samples representing subsurface drainage. Correlation analysis of bioluminescence with mine water quality parameters showed that only water color had a strong association with bioluminescence. This correlation is stronger for surface drainage, than for mine waters from subsurface drainage. Direct measurement of bioluminescence, resulting from adenosine 5`-triphosphate (ATP) using a luminometer, is a fast and reliable method for evaluation of the characteristics of mine waters in real-time.
