Effect of freeze-thaw on freezing point and thermal conductivity of loess

Wang, Songhe; Wang, Qinze; Xu, Jian; Ding, Jiulong

doi:10.1007/s12517-020-5186-2

Cited by 16 publications

(5 citation statements)

References 35 publications

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“…However, due to the irregularity of the soil particles, the particle orientation generally shows strong randomness. It is worth noting that the arrangement and morphological characteristics of the soil particles jointly control the inter-particle friction characteristics (Wang et al 2007(Wang et al , 2020a. The change of these two factors is quite small while showing certain randomness, which explains the slight fluctuation of the friction angle of the soil under WD cycles (Fig.…”

Section: Effect Of Wd Cycles On Microstructurementioning

confidence: 98%

Shear strength and damage characteristics of compacted expansive soil subjected to wet–dry cycles: a multi-scale study

Liu

Jing

2021

Arab J Geosci

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In expansive soil regions, engineering geological disasters frequently occur in wet-dry (WD) environments, which are inseparable from the degradation of soil shear strength and structural damage. This study attempts to assess the underlying mechanisms of shear strength degradation and micro-and mesoscale damage to expansive soil under WD cycles. Recompacted specimens were subjected to several WD cycles, then triaxial shear, nuclear magnetic resonance, and scanning electron microscopy tests were performed. Moreover, the influence of the WD cycles on the shear strength of expansive soil was evaluated. The state-of-the-art image processing and analysis techniques were combined to quantitatively investigate the evolution of the soil micro-and mesostructural characteristics. The results reveal that the deterioration of soil shear strength is primarily embodied in the initial 3 WD cycles, and is mainly due to the severe loss of cohesion (about 51.69%) during this period. Soil meso-cracks were formed under the combined effects of swelling potential and tensile stress, which mainly occurred in three stages: initiation stage (1-2 cycles); propagation stage (3-4 cycles); equilibrium stable stage (5-6 cycles). Indeed, the strength and average width of cracks were increased to varying degrees, which degraded the structural integrity of the soil. In addition, the microstructure of the soil was deeply affected by WD cycles; the total volume of pores increased significantly, the particles roundness decreased marginally, and an isotropic particles orientation was achieved as a whole with local preferential orientation (depolarization). The deterioration of shear strength of the expansive soil may be attributed to alterations in humidity, which causes the clay minerals in the soil to swell and shrink repeatedly, thereby yielding the irreversible fatigue damage of microstructure and propagation of meso-cracks. This work sheds light on the properties of shear strength evolution and mechanisms of structural damage in expansive soils in semi-arid regions.

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Section: Effect Of Wd Cycles On Microstructurementioning

confidence: 98%

Shear strength and damage characteristics of compacted expansive soil subjected to wet–dry cycles: a multi-scale study

Liu

Jing

2021

Arab J Geosci

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“…Referring to the minimum and maximum surface temperatures during the freeze-thaw period in the last 20 years in Yan'an and Yulin, as shown in Figure 5a, the freezing and thawing temperatures in the freeze-thaw cycle test were determined to be −20 °C and 20 °C, each lasting 12 h for one freeze-thaw cycle, as shown in Figure 5b. According to the findings of the earlier studies, the microstructure and strength qualities of loess are mostly affected by the early phases of the freeze-thaw process, and after 20 cycles, its physical and mechanical characteristics gradually stabilize [29][30][31]. Therefore, the precise number of freeze-thaw cycles was chosen at zero, one, three, five, 10, and 20 in this investigation.…”

Section: Freeze-thaw Cycle Testsmentioning

confidence: 99%

“…Therefore, the precise number of freeze-thaw cycles was chosen at zero, one, three, five, 10, and 20 in this investigation. To ensure the stability of the sample in the freeze-thaw process, According to the findings of the earlier studies, the microstructure and strength qualities of loess are mostly affected by the early phases of the freeze-thaw process, and after 20 cycles, its physical and mechanical characteristics gradually stabilize [29][30][31]. Therefore, the precise number of freeze-thaw cycles was chosen at zero, one, three, five, 10, and 20 in this investigation.…”

Section: Freeze-thaw Cycle Testsmentioning

confidence: 99%

Effect of Freeze–Thaw Cycles and Initial Water Content on the Pore Structure and Mechanical Properties of Loess in Northern Shaanxi

Pan

Yang

et al. 2023

Sustainability

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Spalling disease caused by freeze–thaw cycles often occurs on the loess cut-slopes in northern Shaanxi. The deterioration of the pore structure and mechanical strength of loess under a freeze–thaw environment is one of the critical reasons underlying the occurrence of spalling disease in the slopes. In order to explore the effects of freeze–thaw cycles on the pore structure and the mechanical strength of loess, four initial water contents (7%, 9%, 12%, and 14%) and six freeze–thaw cycles (zero, one, three, five, 10, and 20) were considered in this study. Nuclear magnetic resonance (NMR) and triaxial compression tests were carried out to analyze and reveal the mechanisms of effect causing the deterioration of the soil strength that affects the stability of loess cut-slopes. The results showed that the porosity growth increased with the initial water content and continued to increase during the freeze–thaw process until a later stage of the freeze–thaw cycle, when it gradually stabilized. The stress–strain curves were primarily influenced by the number of freeze–thaw cycles, the initial water content of the samples, and the confining pressure. Both the cohesion and the internal friction angle exhibited a decay law that showed a significant decrease, then a slow decrease, and finally stabilization during the freeze–thaw process. Small and micropores were predominant among the pore structures of the loess, while medium pores were the second most common, and large pores were the least common. With the increase in the initial water content, the pores transformed from micropore structures to medium and large pore structures. The soil strength deterioration was primarily driven by the phase changes of the pore water, as well as the water migration during the freeze–thaw process. This study will be beneficial for identifying the characteristics and types of freeze–thaw disease in cut-slope engineering in seasonally frozen loess areas and providing a theoretical reference and design basis for achieving green and sustainable development in slope engineering, management, and maintenance.

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“…In China, most of the loess is in seasonally frozen land areas. Seasonal changes in temperature cause changes in the physical and mechanical properties of soil, which is one of the crucial causes of geology-related engineering disasters [4][5][6][7]. To ensure the safety of construction and engineering operations, it is essential to understand the effects of freeze-thaw (FT) cycling (FTC) on the physical and mechanical properties of loess.…”

Section: Introductionmentioning

confidence: 99%

Shear Strength and Microstructure of Intact Loess Subjected to Freeze‐Thaw Cycling

Liu

Jing

2021

Advances in Materials Science and Engineering

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In the Loess Plateau, seasonal freeze and thaw cause great damage to the mechanical behavior and microstructure of soil, which leads to frequent geological disasters during winter and spring. To investigate the influence of freeze-thaw (FT) cycling (FTC) on the shear strength and microstructure of intact loess, triaxial shear, nuclear magnetic resonance, and scanning electron microscope tests were carried out on soil samples after target FT cycles. The results indicate that the FTC has limited changes to the soil stress-strain curve, but has a significant attenuation effect on the peak deviatoric stress. The peak deviatoric stress was attenuated by FTC but changed insignificantly after ten cycles. The cohesive force decays exponentially with the number of FT cycles, while the internal friction angle increases slightly. Moreover, under FTC, the T2 hydrogen spectra of soil samples showed a multimodal distribution, with the main peak appearing to have two obvious upward shifts that occurred at 6 and 10 FT cycles. Indeed, a depolarization phenomenon related to the directional frequency of soil particles was observed, and the mass fractal dimension of the pore network increased slightly. In an FT environment, the shear strength declines due to accumulated internal microstructural damage. These findings contribute to a better understanding of the response of loess to FTC and provide novel ideas for the prevention of frost damage in loess areas.

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Effect of freeze-thaw on freezing point and thermal conductivity of loess

Cited by 16 publications

References 35 publications

Shear strength and damage characteristics of compacted expansive soil subjected to wet–dry cycles: a multi-scale study

Shear strength and damage characteristics of compacted expansive soil subjected to wet–dry cycles: a multi-scale study

Effect of Freeze–Thaw Cycles and Initial Water Content on the Pore Structure and Mechanical Properties of Loess in Northern Shaanxi

Shear Strength and Microstructure of Intact Loess Subjected to Freeze‐Thaw Cycling

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