Experimental Study on the Freezing Temperatures of Saline Silty Soils

Wan, Xusheng; Lai, Yuanming; Wang, Chong

doi:10.1002/ppp.1837

Cited by 133 publications

(51 citation statements)

References 16 publications

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“…Ion analysis indicated that sodium, chloride and sulfate were dominant in the dissolved salts [16]. The soil samples were rinsed with distilled water to desalinize them until the electrical conductivity (probe: Hydra probe SDI-2) declined to zero.…”

Section: Methodsmentioning

confidence: 99%

The Phase Change Process and Properties of Saline Soil During Cooling

et al. 2017

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Detrimental frost heave and salt expansion may occur in saline soils of cold regions. The severity of these processes depends on the amount of salt precipitation and ice crystal growth in the pore solution at different temperatures. By employing nuclear magnetic resonance, the liquid water fractions in different concentrations of sodium chloride and sodium sulfate saline soils were measured at different temperatures. Based on the theory of solution phase diagram and phase change in porous media, the differences and similarities of phase change between pore solution and free solution were analyzed. The phase change sequence and effects of salt on frozen soils are also discussed. The theoretical and experimental results confirm that the phase diagram can reflect the phase change of pore solutions roughly, and pore size distribution is the cause of differences between the pore solution and free solution. Sodium chloride can mitigate the frost heave of soil, and frost heave and salt expansion occur together when the sodium sulfate soil is frozen.

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Section: Methodsmentioning

confidence: 99%

The Phase Change Process and Properties of Saline Soil During Cooling

et al. 2017

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“…Cooling temperature curve -The cooling temperature curves were obtained by cooling the frozen saline soils with salt contents 0.0%, 0.5%, 1.5%, and 2.5% (the salt is anhydrous Na 2 SO 4 fine particles) from the initial temperature of 10°C. Referring to previous research (Xu et al 2010;Bing and Ma 2011;Wan et al 2015), the freezing temperatures of frozen saline soils can be determined. From the cooling temperature curves (Fig.…”

Section: Influence Of Salt Content On the Shear Strength Of Frozen Samentioning

confidence: 99%

A strength criterion for frozen sodium sulfate saline soil

2016

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Salt content has been proven to be an important influencing factor on the mechanical properties of frozen saline soils, whose strength criterion is different from that of unfrozen saline soils or frozen soils without salts. In this paper, a series of conventional triaxial tests are carried out for frozen saline soils with sodium sulfate at a temperature of -6°C. A strength criterion of the frozen saline soils, including the influence of salt content, is established by using the generalized nonlinear strength theory. Based on conventional triaxial test results, a modified hydrostatic pressure expression is proposed according to the critical strength function of the modified Cam clay model in the meridian plane. The influence of salt content on the shear strength of the frozen saline soils is investigated according to their freezing temperature curves as well as the formation of salt and ice crystals. The relationship between salt content and friction angle is analyzed. The proposed strength criterion of frozen saline soil is proved to be reliable by extrusion elongation triaxial tests. This criterion can reasonably reflect the major nonlinear strength characteristics of frozen saline soils, including the influences of change in salt content, pressure melting, and ice crushing.Key words: sodium sulfate, frozen saline soil, strength criterion, freezing temperature, deviatoric plane.Résumé : La teneur en sel est avérée être un facteur d'influence importante sur les propriétés mécaniques des sols salins congelés, dont son critère de résistance est différent de celle des sols salins dégelés ou des sols gelés sans sels. Dans cet article, une série d'essais triaxiaux classiques sont effectués pour les sols salins congelés avec du sulfate de sodium à la température de -6°C. Un critère de résistance de sols salins congelés, y compris l'influence de la teneur en sel, est établi en utilisant la théorie généralisée de la résistance non linéaire. Sur la base de résultats d'essais triaxiaux classiques, une expression de pression modifiée hydrostatique est proposée, conformément à la fonction de la résistance critique du modèle Cam clay modifié dans le plan méridien. L'influence de la teneur en sel sur la résistance au cisaillement des sols salins congelés est étudiée en fonction de leurs courbes de température de congélation, et aussi la formation de cristaux de glace et de sel. La relation entre la teneur en sel et l'angle de frottement est analysée. Le critère de la résistance proposé de sol salin congelé est prouvé fiable par des essais triaxiaux d'allongement par extrusion. Ce critère peut raisonnablement refléter les principales caractéristiques de résistance non linéaire des sols salins congelés, y compris les influences de l'évolution de la teneur en sel, de la fusion et du broyage de glace sous pression. [Traduit par la Rédaction] Mots-clés : sulfate de sodium, sols salins congelés, critère de résistance, température de congélation, plan déviatorique.

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“…Sulfate soil is a predominant and representative type of sulfate saline soil found in western China (Wan et al, 2015), and sodium sulfate is most prevalent in large areas of the Beilu River on the Qinghai-Tibet Plateau. Therefore, sodium sulfate soil was selected to study salt expansion mechanisms.…”

Section: Experimental Designmentioning

confidence: 99%

An experimental study of salt expansion in sodium saline soils under transient conditions

et al. 2017

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Salt expansion in sulfate saline soils that are widely distributed in northwestern China causes serious infrastructural damages under low-temperature conditions. However, the mechanism of salt expansion under low temperatures is not clear. In this study, we conducted a series of cooling experiments combined with salt crystallization to study this mechanism, and employed an ionic model to calculate the supersaturation ratio of the solution. During the experiments, the strength and the process of salt expansion were examined under different cooling rates and various crystal morphologies. The relationship between temperature and supersaturation ratio under transient conditions was also considered. Results indicate that the initial supersaturation ratio of a sodium sulfate solution is closely related to environmental conditions, and that this ratio decreases with slowing the cooling rates and stabilizing the crystal forms. Higher initial supersaturation ratios lead to an increased non-steady-state zone, resulting in less salt expansion. On the other hand, chloride ion content has a distinct influence on the crystallization supersaturation ratio of the sodium sulfate solution, and higher chloride ion content can inhibit salt expansion in sodium saline soils. These findings help explain salt expansion mechanisms in complex conditions such as seasonally frozen soils, and thus help search for improved methods of preventing salt expansion in sulfate saline soils.

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Experimental Study on the Freezing Temperatures of Saline Silty Soils

Cited by 133 publications

References 16 publications

The Phase Change Process and Properties of Saline Soil During Cooling

The Phase Change Process and Properties of Saline Soil During Cooling

A strength criterion for frozen sodium sulfate saline soil

An experimental study of salt expansion in sodium saline soils under transient conditions

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