Microstructure of unsaturated loess and its influence on strength characteristics

Wei, Yazhi; Yao, Zhihua; Chong, Xiaolei; Zhang, Jianhua; Zhang, Jun

doi:10.1038/s41598-022-05464-9

Cited by 8 publications

(5 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The SO 4 -containing evaporites have a cementation and solidification effect on the maintenance of the structure of loess [ 31 ]. When the soil was disturbed in the column experiment, most of the original cemented contact was destroyed [ 32 ], damaging pores. In this circumstance, the SO 4 -containing evaporites in the cement and the SO 4 -containing evaporites in the closed pores were exposed to the water and dissolved ( Figure 4 ).…”

Section: Discussionmentioning

confidence: 99%

Soil Column Experimental Study on the Effect of Soil Structure Disturbance on Water Chemistry

Long

Huang

Zhang

et al. 2022

IJERPH

View full text Add to dashboard Cite

The changes in soil/rock structure caused by engineering disturbance or earthquakes could affect water chemistry by increasing the reaction surface, enhancing the oxidation condition, or exposing soluble rocks. However, the details of the mechanisms of the disturbance of soil/rock are little known. Based on the soil column experiment, this study analyzed the concentrations of sulfate (SO4), sulfur, and oxygen isotopic composition of SO4 (δ34S-SO4 and δ18O-SO4) in effluent water. The water–rock interaction mechanisms in the disturbed soil and the contribution of this interaction to the SO4 in groundwater were studied. The results suggest that the concentration of SO4 in the first effluent water sample can reach up to 97 mg/L, much higher than that in natural groundwater (6.8 mg/L). The isotopic composition of SO4 further suggested that SO4 in the first effluent water sample was mainly derived from the dissolution of SO4-containing evaporites. The proportion was estimated to be 93%. SO4-containing evaporites accounted for 23% of the SO4 content in all effluent water samples during the experiment. The disturbance of soil structure led to the exposure and dissolution of SO4-containing evaporites, which were initially insoluble under natural conditions. This study is essential to the clarification of the water–rock interaction mechanisms following the changes in soil/rock structures.

show abstract

Section: Discussionmentioning

confidence: 99%

Soil Column Experimental Study on the Effect of Soil Structure Disturbance on Water Chemistry

Long

Huang

Zhang

et al. 2022

IJERPH

View full text Add to dashboard Cite

show abstract

“…They noted that the primary factors affecting the strength and deformation of loess were the cementation, matrix suction, and intergranular porosity ratio. With the advancement of technology, comparable findings can be attained with CT scanning technology to examine the variations of three-dimensional (3D) microstructure of loess during its deformation process (Wei et al 2020;Tang et al 2021;Wei et al 2022;Nan et al 2023).…”

Section: Natural Hazardsmentioning

confidence: 99%

Collapsible characteristics and prediction model of remodeled loess

Fan,

Zhang,

Shi

et al. 2024

Preprint

View full text Add to dashboard Cite

The construction of the open channel projects in the northern Xinjiang region of China often involves traveling through vast areas of loess. The apparent collapsibility of loess is a major concern for engineers as it can lead to uneven deformation and failure of channel slopes. Collapsibility tests and scanning electron microscopy (SEM) analysis were conducted on remolded loess to comprehensively investigate the settlement and deformation mechanisms of collapsible loess from both macro- and micro-perspectives. Furthermore, a prediction model was developed and its applicability was verified. The test results indicated that with the increase of the vertical load, the collapsibility coefficient exhibited a trend of rapid increase followed by slow increase, and eventually stabilized. This trend satisfied a hyperbolic function relationship, which was negatively correlated with the changes of the water content and dry density. SEM analysis on the loess specimens confirmed that collapsible deformation involved a gradual transition from a shelf structure to a mosaic-colloid structure. Factors such as pore size and particle morphology were found to have significant influences on the collapsibility. For prediction purposes, statistical theory and machine learning algorithms were utilized to select variables such as dry density, moisture content, initial porosity ratio, and pressure test parameters. The GA-SVM model had higher accuracy and better applicability. The findings of the current study can provide valuable guide for the construction and management of water-conveyance projects in loess regions.

show abstract

“…Furthermore, to get a thorough understanding of the undrained response of compacted loess is crucial in the instability analysis of earth structures. Previous investigations often focus on the conventional triaxial test method 13 , where soil samples are consolidated under an isotropic stress state. To replicate the K 0 stress state in a triaxial test, a soil sample needs to be consolidated anisotropically with proper control of the stress and deformation of the specimen, through which the lateral constraint of the soil can be fulfilled 14 – 16 .…”

Section: Introductionmentioning

confidence: 99%

On characteristics of K0 value and shear behaviour of loess using triaxial test

Liu,

Xu,

Huang

et al. 2024

Sci Rep

View full text Add to dashboard Cite

Compared with conventional soils, such as sand and clay, little knowledge on the coefficient of lateral earth pressure at-rest (K0) has been established for loess in the current literature. This paper presents an experimental investigation on K0 of compacted loess and the associated impacts on undrained shear behaviour. By adopting a K0 consolidation module in the triaxial system, the K0 stress state for loess samples was achieved through a unique feedback control. During the K0 consolidation, the deviatoric stress (q) increases progressively with the premise that the volumetric strain (εv) of the sample equals to the axial strain (εa). The results show that the K0 value of compacted loess is in a range of 0.28 to 0.53, which is dependent on the packing density and the clay content. A distinguishable decrease of K0 was found in the course of K0 consolidation for the loosely compacted loess sample, whereas a similar trend was not observed in the dense sample. In the undrained shear stage, all loess specimens revealed contractive response in the stress path (q-p’) diagram, which can be quantified by a modified collapsibility index (Ic). The index is consistently higher for the K0 consolidated loess samples than for the isotropic ones. The experimental results indicate a strong impact of the initial stress state on the shear behaviour of compacted loess.

show abstract

Microstructure of unsaturated loess and its influence on strength characteristics

Cited by 8 publications

References 39 publications

Soil Column Experimental Study on the Effect of Soil Structure Disturbance on Water Chemistry

Soil Column Experimental Study on the Effect of Soil Structure Disturbance on Water Chemistry

Collapsible characteristics and prediction model of remodeled loess

On characteristics of K0 value and shear behaviour of loess using triaxial test

Contact Info

Product

Resources

About