A new model for capturing void ratio-dependent unfrozen water characteristics curves

Mu, Qingyi; Ng, Charles Wang Wai; Zhou, Chao; Zhou, Guomei; Liao, Hongjian

doi:10.1016/j.compgeo.2018.04.019

Cited by 30 publications

(18 citation statements)

References 23 publications

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“…The hysteresis of SFCC was also observed in previous experimental studies (Bittelli et al, 2003; Tian et al, 2017). According to the SFCC model developed by Mu et al (2018), the capillary pressure at the ice–water interface ( u i – u w , where u i and u w are the ice and water pressures, respectively) increases when soil temperature decreases. Water in a given pore would freeze when the capillary pressure increases to 2σ iw cos(α)/ r , where σ iw , α, and r are the surface tension coefficient, contact angle, and pore radius, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…It clearly shows that the unfrozen water retention capacity of clay increases with increasing confining stresses. As explained above, the phase change between ice and water within a soil specimen can be described using the theory of capillarity (Tian et al, 2017; Mu et al, 2018). The void ratio of clay decreases by 33.7% when confining stress increases from 30 to 200 kPa (see Table 2), inducing a significant reduction of soil pore size.…”

Section: Resultsmentioning

confidence: 99%

“…This is due to the freezing point depression attributed to the surface tension at the ice–water interface (Spaans and Baker, 1995, Zhou et al, 2018). According to Kelvin's equation, the freezing point depression is more significant when the radius of ice–water interface is smaller (Lebeau and Konrad, 2012; Mu et al, 2018). The relationship between temperature and unfrozen water content is defined as the soil freezing characteristic curve (SFCC).…”

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confidence: 99%

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Stress Effects on Soil Freezing Characteristic Curve: Equipment Development and Experimental Results

Mu¹,

Zhou

et al. 2019

Vadose Zone Journal

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Core Ideas A triaxial apparatus is developed to measure stress‐dependent SFCC. Unfrozen water content of clay and sand increases with increasing confining stress. Stress effects on the SFCC of clay are more significant than sand. The soil freezing characteristic curve (SFCC) defines the relationship between soil temperature and unfrozen water content. This curve is important for predicting water flow and heat conduction in frozen soils, as well as freezing heave and thawing settlement. So far, SFCCs reported in the literature were usually determined at zero stress. To investigate stress effects on SFCC, a stress‐ and temperature‐controlled triaxial apparatus was developed in this study. The unfrozen volumetric water content was measured using a newly developed noninvasive time domain reflectometry (TDR) probe. The new apparatus was used to measure SFCCs of two typical soils (i.e., clay and sand) at different stress conditions (i.e., 30, 100, and 200 kPa). Each specimen was subjected to compression, and then a cycle of freezing and thawing. As expected, for both soils, the saturated water content prior to freezing was smaller at higher stresses because of compression. During the subsequent freezing and thawing, the soil specimen at a higher stress was able to retain more liquid water than that at a lower stress. The higher unfrozen water retention capacity at higher stresses is mainly because the pore size of a soil specimen becomes smaller during compression. Hence, more water can retain a liquid state due to the enhanced capillarity. On the other hand, stress effects on the SFCC were found to be more significant for clay than for sand. This is likely because the stress‐induced change in pore size distribution is larger in clay due to its higher compressibility.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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Stress Effects on Soil Freezing Characteristic Curve: Equipment Development and Experimental Results

Mu¹,

Zhou

et al. 2019

Vadose Zone Journal

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“…It should be noted that unfrozen water may reduce the strength of frozen soils owing to the role of the lubricant [ 41 ]. In addition, the unconfined compressive strength tends to decrease with the increase in N because more unfrozen water may remain on the soil surface as repetitive loading reduces the number of voids [ 42 , 43 ]. However, the unconfined compressive strength of the sand-dominant mixture increases as the SF and N increase, which induce an increase in the unfrozen water content.…”

Section: Discussionmentioning

confidence: 99%

Strength Characteristics of Sand–Silt Mixtures Subjected to Cyclic Freezing-Thawing-Repetitive Loading

Lee

Han

et al. 2020

Sensors

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Daily freezing-thawing-repetitive loading is a critical factor affecting soil stability. This study assesses the strength of sand–silt mixtures with various silt fractions (SFs) subjected to cyclic freezing-thawing-repetitive loading. Specimens with SF of 0–100% were prepared with a fixed relative density of 60%. The number of repetitive loadings (N) was 1, 100, and 1000 for each specimen with different SFs. After three cycles of freezing-thawing-repetitive loading, the specimens were frozen at −5 °C for the uniaxial compression test. Test results show that the change in relative density (∆Dr) increases with the increase in SF up to 30% and decreases as SF increases beyond 30% owing to the change in the void ratio. The volumetric unfrozen water content (θu) increases with the increase in both SF and N owing to the effect of the physicochemical characteristics of soils on small voids. Unconfined compressive strength of sand-dominant mixtures (SF ≤ 30%) is reinforced by ∆Dr. By contrast, for silt-dominant mixtures (SF > 30%), the unconfined compressive strength decreases with the increase in θu and N due to lubricant role and sands dispersion. Thus, the effects of SF and N should be considered for sand–silt mixtures that have a probability to undergo cyclic freezing-thawing-repetitive loading.

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“…There is a wide range of SFCCs as a result of the complex relationships between soil texture, pore geometry, solute content, freezing point depression, soil saturation and other physical properties of freezing soils. These physical factors make SFCCs difficult to predict accurately using empirical models that are limited to specific reference or measured soils (Mu et al, 2018;Amiri et al, 2018). Physical models are intended to be more transferable, but rely on detailed soil parameters such as the specific surface area of the soil, grain size analysis, polarity of soil particles and other hard-to-collect data (Wang et al, 2017;Bai et al, 2018).…”

Section: Constructing An Sfccmentioning

confidence: 99%

A Repository of 100+ Years of Measured Soil Freezing Characteristic Curves

Devoie

Gruber

McKenzie

2022

Preprint

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Abstract. Soil freeze-thaw processes play a fundamental role in the hydrology, geomorphology, ecology, thermodynamics and soil chemistry of a cold-regions landscape. In understanding these processes, the temperature of the soil is used as a proxy to represent the soil ice content through a soil freezing characteristic curve (SFCC). This mathematical construct relates the soil ice content to a specific temperature for a particular soil. SFCCs depend on many factors including soil properties (e.g., porosity, composition, etc.), soil pore water pressure, dissolved salts, (hysteresis in) freezing/thawing point depression, and degree of saturation, all of which can be site-specific and time varying. SFCCs have been measured using various methods for diverse soils since 1921, and to date this data has not been broadly compared, in part because it has not previously been compiled in a single data set. The dataset presented in this publication includes SFCC data digitized or received from authors, and includes both historic and modern studies. The data is stored in an open-source repository, and an R package is available to facilitate its use. Aggregating the data has pointed out some data gaps, namely that there are few studies of coarse soils, and comparably few in-situ measurements of SFCCs in mountainous environments. It is hoped that this dataset will aid in the development of SFCC theory, and improve SFCC approximations in soil freeze-thaw modelling activities.

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A new model for capturing void ratio-dependent unfrozen water characteristics curves

Cited by 30 publications

References 23 publications

Stress Effects on Soil Freezing Characteristic Curve: Equipment Development and Experimental Results

Stress Effects on Soil Freezing Characteristic Curve: Equipment Development and Experimental Results

Strength Characteristics of Sand–Silt Mixtures Subjected to Cyclic Freezing-Thawing-Repetitive Loading

A Repository of 100+ Years of Measured Soil Freezing Characteristic Curves

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