Hydraulic path dependence of shear strength for compacted loess

Chen, Pan; Jia, Shengao; Wei, Xiaoqi; Sun, Peide; Yi, Panpan; Wei, Changfu

doi:10.1016/j.jrmge.2022.12.006

Cited by 8 publications

(5 citation statements)

References 34 publications

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“…However, with prolonged leaching time, there is a gradual rise in zinc content, hindering mineralization reactions and causing a gradual increase in the permeability coefficient. This observation is in line with the findings of Wang et al [42]. Further work on the statistical analysis, Zeta test results against loess contaminated with Zn 2+ and the change in shear strength of loess contaminated with Zn 2+ under different coaxial loads is still ongoing and the results will be discussed in another paper.…”

Section: Response Mechanism Of Seepage Behaviorsupporting

confidence: 89%

“…Additionally, the adsorption of Zn 2+ and its DDL effect compress the diffusion layer, enhancing the presence of free water channels. The increase in seepage time leads to a gradual increase in the permeability coefficient, as supported by Chen et al [42]. Furthermore, studies by Jiang et al [13], Huang et al [36], Xing et al [37], Kang et al [38], Li et al [39], and Wang et al [25] suggest that carbonate precipitation enhances particle bridging through the adsorption/encapsulation of sand-clay mixtures, thereby enhancing erosion resistance.…”

Section: Seepage Behavior Of Modified Loessmentioning

confidence: 78%

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Feasibility of Microbially Induced Carbonate Precipitation to Enhance the Internal Stability of Loess under Zn-Contaminated Seepage Conditions

He,

Guo,

Zhang

2024

Buildings

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Loess is widely distributed in Northwestern China and serves as the preferred engineering construction material for anti-fouling barriers. Heavy metal contamination in soil presents significant challenges to the engineering safety of vulnerable loess structures. Hence, there is an urgent need to investigate the impact of heavy metal ions on their percolation performance. In order to investigate the effectiveness of microbially induced carbonate precipitation (MICP) using Sporosarcina pasturii (CGMCC1.3687) bacteria in reducing internal seepage erosion, a saturated permeability test was conducted on reshaped loess under constant water head saturation conditions. The response of loess to deionized water (DW) and ZnCl2 solution seepages was analyzed by monitoring changes in cation concentration over time, measuring Zeta potential, and using scanning electron microscopy (SEM). The results indicate that the hydrolysis of Zn2+ creates an acidic environment, leading to the dissolution of carbonate minerals in the loess, which enhances its permeability. The adsorption of Zn2+ ions and the resulting diffusion double-layer (DDL) effect reduce the thickness of the diffusion layer and increase the number of free water channels. Additionally, the permeability of loess exposed to ZnCl2 solution seepage significantly increased by 554.5% compared to loess exposed to deionized water (DW) seepage. Following the seepage of ZnCl2 solutions, changes in micropore area ratio were observed, decreasing by 48.80%, while mesopore areas increased by 23.9%. MICP treatment helps reduce erosion and volume shrinkage in contaminated loess. Carbonate precipitation enhances the erosion resistance of contaminated loess by absorbing or coating fine particles and creating bridging connections with coarse particles. These research results offer new perspectives on enhancing the seepage properties of saturated loess in the presence of heavy metal erosion and the geochemical mechanisms involved.

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Section: Response Mechanism Of Seepage Behaviorsupporting

confidence: 89%

Section: Seepage Behavior Of Modified Loessmentioning

confidence: 78%

Feasibility of Microbially Induced Carbonate Precipitation to Enhance the Internal Stability of Loess under Zn-Contaminated Seepage Conditions

He,

Guo,

Zhang

2024

Buildings

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“…The change process of the m ε is "rising first and then falling" type curve, and the peak value of the m ε can be used as the parameter of the maximum comprehensive structural potential before the damage of in situ loess, namely, the initial structural parameter (m ′ ε ) [27]. It reflects the structural properties of the loess in the absence of external disturbance (rainfall, loading, and disturbance).…”

Section: The Effect Of Combined Water On Structural Propertiesmentioning

confidence: 99%

Mechanical Properties of In Situ Loess under Different Combined Water State Macroscopic and Mesoscopic Studies

Wang

Mao

et al. 2023

Geofluids

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To study the mechanisms of strong and weak combined water on the mechanical properties of in situ loess deformation and strength, triaxial compression tests with different combined water contents were carried out to in situ loess in a region of Shaanxi Province, China. The influence on the mechanical properties and structural variation of in situ loess was discussed from the perspective of combined water. The endogenous factors of deformation and strength properties of in situ loess in triaxial tests were investigated from a fine-scale perspective by combining numerical simulations of discrete elements. The results show that the failure specimen under the condition of strong combined water has an obvious shear band and shows brittle failure. The failure mode of soil samples under weak combined water is characterized by no obvious cracks and bulging, which is plastic failure. The water content at the boundary of strong and weak combined water is the boundary to distinguish weak and strong strain hardening. With the increase of combined water, the ultimate strength, the structural strength, and structural parameters decrease, and the initial structural parameters decrease nonlinearly, resulting in the decrease of soil structure and deformation resistance. Weak combined water is the main factor affecting soil structure. The particle flow numerical simulation explains the whole process of triaxial test of in situ loess from macro to meso and explains from the meso perspective that the structural strength change of intact loess under different combined water contents is mainly caused by the change of contact force and pore between particles.

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“…To obtain the pore size distribution curve (PSD) of the soil using the T 2 distribution data obtained by NMR, a key parameter is required, namely, the surface relaxation rate. In this paper, a relaxation rate of 14.92 µm/ms reported in the reference [20] is used, and PSD curves for composite soils with different fines content are obtained as shown in Figure 6, where the vertical axis f is frequency, representing the ratio of pore volume with the corresponding size to the total pore volume. Similar to Figure 3, at lower fines content, the pore size distribution curve first shifts to the right and then moves to the left as the fines content increases.…”

Section: Effect Of Fines Content On the Pore Size Distribution Curve ...mentioning

confidence: 99%

Effect of Fines Content on Pore Distribution of Sand/Clay Composite Soil

Wang¹,

Chen

et al. 2023

Sustainability

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Plant sand fixation is the most durable and environmentally friendly sand mitigation measure for windblown sand hazards. For aeolian–sand composite soil, the fines content is the main factor affecting the pore size distribution characteristics and determines the soil water retention characteristics. Sandy soil with uniform particle size was used as the material, low-plasticity clay as a fine particle, and composite soils with different fines content were prepared. The evolution of the pore size distribution of composite soils was quantitatively determined using low-field nuclear magnetic resonance technology, and the influence of the fines content on the pore size distribution was obtained. The results show that as the fines content increases, the pore size first increases and then decreases. The pore size distribution curve gradually changes from a single-peak structure to a double-peak structure and becomes a unimodal structure again. The corresponding dominant pore size of composite soils increases first and then decreases with the increase in the fines content. A critical fine particle content is identified to control the strong local honeycomb pore structure of composite soils, which provides a theoretical basis for the material selection and design of plant sand fixation measures.

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Hydraulic path dependence of shear strength for compacted loess

Cited by 8 publications

References 34 publications

Feasibility of Microbially Induced Carbonate Precipitation to Enhance the Internal Stability of Loess under Zn-Contaminated Seepage Conditions

Feasibility of Microbially Induced Carbonate Precipitation to Enhance the Internal Stability of Loess under Zn-Contaminated Seepage Conditions

Mechanical Properties of In Situ Loess under Different Combined Water State Macroscopic and Mesoscopic Studies

Effect of Fines Content on Pore Distribution of Sand/Clay Composite Soil

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