Permeability of loess from the South Jingyang Plateau under different consolidation pressures in terms of the three-dimensional microstructure

Wei, Ya-ni; Fan, Wen; Yu, Ningyu; Deng, Longsheng; Wei, Tingting

doi:10.1007/s10064-020-01875-y

Cited by 22 publications

(9 citation statements)

References 48 publications

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“…e rapid increase, rapid dissipation, and sudden stabilization of pore water pressure (see Figure 4) under impact indicate a rapid transition between the drained and undrained condition of the soil. During the short period of impact, the soil structure becomes denser [29]; the pore volume decreases [30]; the pore water pressure increases; and the soil changes from a drained condition to an undrained condition. In the process of decreasing pore water pressure, the soil changes back to a drained condition.…”

Section: Discussionmentioning

confidence: 99%

“…Most of the aggregate in the sandy silt structure is composed of silt and clay particles, and the clay particles often act as cement or coating for the silt particles (see Figure 9(a)) [37,38]. Under the impact of the landslide thrust, the structure of silt and clay is disrupted and compacted [29], and the volume of the pores decreases (see Figure 9(b)) [30]. When the contact between the soil particles is completely replaced by pore water (see Figure 9(c)), the soil loses its shear strength and reaches the liquefied state.…”

Section: Mechanism Of Impact-induced Liquefactionmentioning

confidence: 99%

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Impact‐Induced Liquefaction Mechanism of Sandy Silt at Different Saturations

Duan

Chenxi

et al. 2021

Advances in Civil Engineering

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Landslide-induced liquefaction has received extensive attention from scholars in recent years. In the study of loess landslides in the southern Loess Plateau of Jingyang, some scholars have noted the liquefaction of the near-saturated sandy silt layer that is caused by the impact of loess landslides on the erodible terrace. The impact-induced liquefaction triggered by landslides is probably the reason for the long-runout landslides on the near-horizontal terrace. In order to reveal the mechanism of impact-induced liquefaction, this paper investigates the development of pore pressure and the impact-induced liquefaction of sandy silt under the influence of saturation through laboratory experiments, moisture content tests, and vane shear tests. It has been found that both the total pressure and pore water pressure undergo a transient increase and decrease at the moment of impact on the soil, which takes 40–60 ms to complete and only about 20 ms to arrive at the peak. Moreover, silty sand with a saturation of more than 80° was liquefied under the impact, and the liquefaction occurred in the shallow layer of the soil body. The shear strength of the liquefied part of the soil is reduced to 1.7∼2.8 kPa. Soils with lower saturation did not liquefy. The mechanism of the impact-induced liquefaction can be described as follows: under impact, the water in the soil gradually fills the pores of the soil body as the pore size decreases, and when the contact between the soil particles is completely replaced by pore water, the soil body loses its shear strength and reaches a liquefied state. Soils in the liquefied state have a very high permeability coefficient, and the water inside the soil body migrates upward as the particles settle, resulting in high-moisture content in the upper soil.

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Section: Discussionmentioning

confidence: 99%

Section: Mechanism Of Impact-induced Liquefactionmentioning

confidence: 99%

Impact‐Induced Liquefaction Mechanism of Sandy Silt at Different Saturations

Duan

Chenxi

et al. 2021

Advances in Civil Engineering

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“…Macropores are more sensitive to compaction compared to micropores [23,68]. During soil compaction or consolidation, larger pores close first [53,[69][70][71][72][73]. is evolution of soil structure affects the permeability and r k variations during soil static compression.…”

Section: Shock and Vibrationmentioning

confidence: 99%

A Conceptual Model and Evaluating Experiments for Studying the Effect of Soil Deformation on Its Permeability

Enayat

Shoaei

Nikudel

2021

Shock and Vibration

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Soil structure and void ratio are the major factors that control the permeability changes during soil deformation. In this research, we proposed and tested a conceptual model considering these two factors based on the concept of permeability anisotropy. This model, which is expressed as k(e) graph, determines the total k values that soil can achieve and shows that as deformation proceeds, soil permeability passes through a specific zone in the k(e) graph. Thus, by deforming a soil sample, measuring its permeability during deformation, and comparing the results using the k(e) graph, it might be possible to predict deformation effects on the permeability. To evaluate this conceptual model, we designed and built a special apparatus to carry out two sets of experiments. The first set was performed to achieve the k(e) graph during static compression based on the conceptual model; and the second set was conducted to investigate the permeability changes relative to k(e) graph during simple shear deformation in constant volume condition. Our results show that the theoretical k(e) graph agrees more with the measured k(e) graph in medium to dense samples that might have no macropore. In addition, particles’ preferential orientation and/or anisotropic permeability were not changed during shear deformation due to three possible causes: deformation done in constant volume deformation, relatively low shear strain, and shearing along particle orientation. Void ratio and particle orientation are associated with each other, and soil shearing with constant void ratio might cause the anisotropy of permeability to be relatively constant. Thus, it is needed to design and build a new complex apparatus or use a special method for testing how permeability changes within the k(e) graph zone during soil deformation.

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“…ere is a close relationship between dry density and permeability [16,17]. e stress environment, temperature, and plant roots around loess will have a certain impact on permeability [18,19]. On the one hand, the change in temperature will affect the viscosity of water, on the other hand, it may affect the soil structure, and the overall permeability will increase with the increase of temperature [20].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Influence of Soil Structure Index on Loess Permeability

Ren

Wang

Wentong

2022

Advances in Materials Science and Engineering

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In order to study the effects of dry density and initial water content on the permeability characteristics of loess, the saturated permeability tests of undisturbed loess and remolded loess were carried out in Lanzhou New Area. The anisotropy of undisturbed loess under two factors is analyzed and compared, and the permeability difference between undisturbed loess and remolded loess is also analyzed. The results show that the structure of loess has an important impact on the permeability characteristics, and the dry density is an important structural parameter. The natural structure of undisturbed loess has obvious anisotropy. Under different pore conditions and water contents, it will show the anisotropic behavior of permeability. The influence of water content on permeability is mainly reflected in the influence on the properties of cement between soil particle skeletons. Under different dry density conditions, the influence of water content on permeability is different. When the pore structure is relatively compact, the influence of water content is more obvious. In practical engineering, these two factors need to be comprehensively considered in order to accurately describe the permeability distribution of loess. This study can provide some theoretical guidance for the construction of relevant loess projects.

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Permeability of loess from the South Jingyang Plateau under different consolidation pressures in terms of the three-dimensional microstructure

Cited by 22 publications

References 48 publications

Impact‐Induced Liquefaction Mechanism of Sandy Silt at Different Saturations

Impact‐Induced Liquefaction Mechanism of Sandy Silt at Different Saturations

A Conceptual Model and Evaluating Experiments for Studying the Effect of Soil Deformation on Its Permeability

Experimental Study on the Influence of Soil Structure Index on Loess Permeability

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