Thermal Conductivities of Remolded and Undisturbed Loess

Zhen, Zuo-lin; Ma, Guoliang; Gai, Yu-xi; Su, Zhenyan

doi:10.1061/(asce)mt.1943-5533.0002595

Cited by 17 publications

(3 citation statements)

References 36 publications

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“…During the formation of soil, various physical and chemical interactions form associations between particles that provide structural strength, and soil with structural strength is called structural soil [1,2]. The structural strength of soil causes differences in the engineering properties of undisturbed and remolded soils [3,4]. In the meantime, soils with special material composition, structure, and engineering geological properties are called special soils and are widely distributed and applied in building materials worldwide.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Structural Strength of Expansive Soil in a Seasonally Frozen Region

Sun,

Song,

Niu

et al. 2024

Buildings

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The existence of structural strength in undisturbed soil results in its distinct characteristics compared to remolded soil. Under the influence of freeze–thaw cycles, this difference may easily cause geotechnical disasters in cold regions. This study aimed to analyze and discuss the expression degree and influencing factors of the structural strength of expansive soil. The unconfined compressive strength (UCS) test, high-pressure consolidation test, and microscopic test were performed on expansive soil retrieved from a seasonally frozen region. Moreover, sensitivity parameters, including stress sensitivity (St.qu, St.σk) and strain sensitivity (St.ɛu, St.Cc), were applied to explore the expression degree and influencing factors of structural strength in a seasonally frozen region. The results reveal that the undisturbed samples have better structural connection and particle arrangement than the remolded samples. However, the primary fractures have a certain degrading effect on the strength of the undisturbed soil as influenced by a seasonally frozen region. With the increase in water content and the decrease in density, the expression degree of the structural strength in terms of compressive strength and the ability to resist deformation enhances under the unconfined condition. By contrast, the expression degree increases in strength and decreases in ability under the confined condition. Furthermore, the effect mechanisms of the basic property, particle composition, structural linkage, lateral confinement, and historical role on the structural expression were analyzed.

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Section: Introductionmentioning

confidence: 99%

Investigation of the Structural Strength of Expansive Soil in a Seasonally Frozen Region

Sun,

Song,

Niu

et al. 2024

Buildings

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show abstract

“…Xu et al [3] and Zhang et al [13] found the relationships between the thermal conductivity of a silty clay and various influence factors during a freezing-thawing process. Zhen et al [14] analyzed the effects of dry density and water content on the thermal conductivities of remolded loess and undisturbed loess. Ivan V. Nikolaev et al [15] completed the test of thermal conductivity of sand, for temperatures ranging from 2°C to 92°C and water contents varying from complete dryness to full saturation.…”

Section: Introductionmentioning

confidence: 99%

The Variation Mechanism of Thermal Properties of Loess with Different Water Contents during Freezing

Dong

Liu

2021

Advances in Civil Engineering

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The thermal properties of soils are affected by many factors, such as temperature, water content, and structure. Based on the transient plane source method of thermal physics, the thermal properties of loess with different water content during the freezing process were tested. We analyzed the variation mechanism of thermal properties from the perspective of phase change. Based on the Pore/Particle and Crack Analysis System (PCAS) and theory of heat transfer, we then analyzed the microstructure and heat conduction process of loess. And a calculation model of volumetric heat capacity of frozen soil was presented. The results show that, in the major phase transition zone, the variation of the thermal properties of loess with temperature is the most significant. And the thermal diffusivity increases sharply with the significant increase of thermal conductivity and the rapid decrease of volumetric heat capacity. Moisture content not only increases the thermal conductivity and volume heat capacity of loess but also makes the influence of temperature on the thermophysical parameters more significant. The effect of temperature on thermal properties is mainly due to the change of heat transfer media caused by phase transition of water-ice, followed by the change of thermal properties of heat transfer media such as soil particles, water, ice, and air with temperature. Increasing the water content reduces the contact thermal resistance between soil particles because of the increase in the thickness of the water film on the surface of soil particles and the thermal conductivity of the heat transfer medium between particles, thus changing the thermal properties of soils.

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“…e test results showed that the strength and modulus of loess soil were improved by 11 freeze-thaw cycles. Zhen et al [37] studied the thermal conductivities of undisturbed and remolded Malan loess collected from the first terrace of the Yellow River and found that at a saturation degree and a dry density, the thermal conductivity of undisturbed loess was larger than that of remolded loess. To improve strength and deformation behavior of loess, stabilization of loess has been attempted using different materials such as novel reactive magnesia-bearing binders [38], lime and fly ash piles [39], and nanoclay [40].…”

Section: Introductionmentioning

confidence: 99%

Disturbance Evolution Behavior of Loess Soil under Triaxial Compression

Guo

2020

Advances in Civil Engineering

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This paper presents an investigation into the evolution law of the structural effects of Xi’an loess soil, based on the disturbed state concept. First, a series of consolidated and drained triaxial compression tests were performed on undisturbed and remoulded loess samples prepared at five different moisture contents and tested at four different confining pressures. Second, two disturbance functions with different parameters were proposed to quantify mathematically the structural effects of loess. Finally, the proposed disturbance functions were validated against documented test results by other researchers. The results indicated that the single-parameter disturbance function, with the deformation modulus as its parameter, provides convenience for application but takes no account of the respective contributions of deviatoric stress and mean stress to the disturbance evolution behavior of loess. The double-parameter disturbance function, with the shear and bulk moduli as its parameters, is capable of distinguishing these respective contributions and reflects well the disturbance evolution behavior of loess under various moisture contents and confining pressures. The effects of moisture content and confining pressure on the parameters of the disturbance functions were found to be unsteady. The proposed disturbance functions lay the foundation for establishing a constitutive model for loess accounting for the structural effect.

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Thermal Conductivities of Remolded and Undisturbed Loess

Cited by 17 publications

References 36 publications

Investigation of the Structural Strength of Expansive Soil in a Seasonally Frozen Region

Investigation of the Structural Strength of Expansive Soil in a Seasonally Frozen Region

The Variation Mechanism of Thermal Properties of Loess with Different Water Contents during Freezing

Disturbance Evolution Behavior of Loess Soil under Triaxial Compression

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