Microscale evidence for and formation mechanisms of shear-strength anisotropy of a loess-paleosol sequence since the late Early Pleistocene: The case study of the Xiushidu profile, Southern Chinese loess Plateau

Zhang, Qiying; Qian, Hui; Xu, Panpan; Hou, Kai; Zhang, Yuting; Qu, Wengang; Lin, Tao; Chen, Yao

doi:10.1016/j.catena.2022.106228

Cited by 13 publications

(3 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From different directions of the soil sample, the muddy clay exhibited a more obvious anisotropic structure in the vertical and horizontal directions, mainly reflected in the high directionality of its horizontal particles or aggregates. The layered deposition of cohesive soil during the geological structure process may be the main reason for this phenomenon [51]. In addition, the particle contact mode was edge-surface contact, and the pore type was the coexistence of intergranular pores and intragranular pores.…”

Section: Differentiation Of Microstructures In Different Directionsmentioning

confidence: 99%

Anisotropy Study on the Process of Soil Permeability and Consolidation in Reclamation Areas: A Case Study of Chongming East Shoal in Shanghai

Yao,

Wang,

et al. 2023

Buildings

View full text Add to dashboard Cite

Anisotropic permeability is of great significance for assessing the consolidation and drainage mode of soil layers in reclamation areas, as well as for preventing and controlling ground settlement after project construction. This paper analyzes the anisotropic permeability of the inland and nearshore soil layers in Chongming East Shoal, Shanghai, and the formation mechanism of anisotropic permeability through permeability and scanning electron microscope (SEM) tests. The results highlight that compared with dredger fill and sandy silt, the horizontal permeability coefficient of underlying soft clay (USC) is significantly higher than its vertical permeability coefficient, which is more significant in nearshore USC. Interestingly, the upper clay (21.5 m) in the thickest clay layer shows greater anisotropic permeability than the lower clay (41.5 m). Due to the instability of seepage channels, the USC anisotropic permeability increases in a fluctuating manner as the hydraulic gradient increases. Microstructural parameters are used to reveal the mechanism of anisotropic permeability, which shows that a simple soil skeleton and structure, strong particle orientation, decreased particle abundance, increased particle roundness, decreased particle contact area, and increased pore area all contribute to the enhancement of permeability. Moreover, micro-parameters have been proposed to evaluate anisotropic permeability in terms of the effective seepage-pore area. This approach addresses the constraint of water films on the permeability efficiency of USC particles.

show abstract

Section: Differentiation Of Microstructures In Different Directionsmentioning

confidence: 99%

Anisotropy Study on the Process of Soil Permeability and Consolidation in Reclamation Areas: A Case Study of Chongming East Shoal in Shanghai

Yao,

Wang,

et al. 2023

Buildings

View full text Add to dashboard Cite

show abstract

“…For example, in the Loess Plateau area, washing holes are mostly develop in the recent loess layer and the Malan loess layer (Peng et al, 2018). This is because the surface soil layer in the upper part of the recent loess layer and the palaeosol layer in the Malan loess layer have high clay contents, are hard and compact, and are comparatively resistant to water erosion, while the recent loess layer and the Malan loess have high sand contents and are loose and porous, leading to a low resistance to erosion (Jia et al, 2021; Zhang et al, 2022). The gullies in the Yuanmou Dry‐Hot Valley formed in an area with Quaternary fluvial‐lacustrine deposits, and the cross‐sections of gully heads feature alternating clayey and sandy layers.…”

Section: Formation Factorsmentioning

confidence: 99%

Tiny niche terrain induces gully headcut retreat

Wang,

Cai,

Deng

2024

Earth Surf Processes Landf

View full text Add to dashboard Cite

Gully erosion damages land resources and endangers human productivity and life, making it a key issue in global research on soil erosion nowadays. Gully headcut retreat (GHR) is the main form of gully erosion. Tiny concave features can be found in many retreating gully heads worldwide, and they are referred to as “niche terrain” in this study. To investigate the association between niche terrain and GHR, relevant research was reviewed on niches and stability analysis of gully heads with niches was modelled and analysed. Studies have shown that not all niches worldwide are identical due to regional differences in internal material–external environmental conditions. Special soil properties, joints, and cracks are the internal material conditions that lead to the formation of niche. External conditions include climate conditions, vegetation conditions, and topography. Water is the driving force for the formation of niche, while vegetation and topography are key factors. Niches can be regarded as the initial stage of GHR in areas where gully erosion is intense. In general, GHR is a composite cyclical process dominated by hydraulic erosion in the early stage and gravitational erosion in the late stage, including niche formation, inward concave formation, free face formation, overhanging soil collapse, and niche reformation. In this study, a model of gully head stability is applied, and it is found that the stability‐based factor of safety decreases exponentially with increasing niche height and crack depth, increases exponentially with increasing niche angle, and decreases quadratically with increasing catchment slope. Summarizing the common characteristics of niche terrains worldwide can facilitate the study of the evolution of gully erosion globally.

show abstract

“…Loess, which covers approximately 9.3% of the Earth's land surface, is commonly found in arid and semi-arid regions [1][2][3]. It is utilized in various engineering projects for foundations, building materials, and constructing underground anti-fouling barriers to treat heavy metal-contaminated soil.…”

Section: Introductionmentioning

confidence: 99%

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

He,

Guo,

Zhang

2024

Buildings

View full text Add to dashboard Cite

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.

show abstract

Microscale evidence for and formation mechanisms of shear-strength anisotropy of a loess-paleosol sequence since the late Early Pleistocene: The case study of the Xiushidu profile, Southern Chinese loess Plateau

Cited by 13 publications

References 62 publications

Anisotropy Study on the Process of Soil Permeability and Consolidation in Reclamation Areas: A Case Study of Chongming East Shoal in Shanghai

Anisotropy Study on the Process of Soil Permeability and Consolidation in Reclamation Areas: A Case Study of Chongming East Shoal in Shanghai

Tiny niche terrain induces gully headcut retreat

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

Contact Info

Product

Resources

About