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Song Y, Wang JQ, Chen XJ, Yu SZ, Ban RL, Yang X, Zhang X, Han Y. Study the effects of dry-wet cycles and cadmium pollution on the mechanical properties and microstructure of red clay. Environ Pollut 2022; 302:119037. [PMID: 35245622 DOI: 10.1016/j.envpol.2022.119037] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 02/05/2022] [Accepted: 02/17/2022] [Indexed: 06/14/2023]
Abstract
In order to study the effect of cadmium ions on the mechanical properties and micro-structure characteristics of the red clay in Guilin, we have conducted triaxial test and the scanning electron microscope tests to analyze the effects of cadmium ion concentration and the number of dry and wet cycles on the mechanical properties and micro-structure changes of the red clay. The results showed the effects of cadmium ions and dry-wet cycles destroy the structure of red clay. The cohesive force of red clay decreases with the increase of cadmium ion concentration, and the internal friction angle first increases and then decreases. With the rise in the number of dry and wet cycles, the cohesive force of cadmium-contaminated red clay first increases and then decreases, and the angle of internal friction rises gradually. Under the action of different cadmium ion concentrations, the stress-strain curve is strain hardening. With the concentration of cadmium ions increases, the strain hardening becomes more apparent; the peak value reached faster. and the axial strain corresponding to the peak value of the line decreases. With the increase in the number of wet and dry cycles, the volume of cadmium-contaminated red clay shrinks and its compactness increases; it gets the peak shear strength faster during the shearing process, and its peak value becomes larger and larger. The main reason for the phenomenon is that cadmium ions destroy the cementation between the particles. The soil particles are mainly in point contact which loosens the structure of the soil; on the other hand, the thickness of the surface diffusion layer of the clay particles increases through chemical action, The exchange of cations increases the porosity of the soil and weakens its strength. The dry-wet cycle shrinks the volume of the red clay, and the soil particles are mainly in surface contact; as the number of dry-wet cycles increases, the soil particles connection is closer, the soil porosity decreases and the strength increases.
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Affiliation(s)
- Yu Song
- College of Civil and Architecture Engineering, Guilin University of Technology, Guilin, China; Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering, Guilin, China.
| | - Jian-Qiang Wang
- College of Civil and Architecture Engineering, Guilin University of Technology, Guilin, China; Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering, Guilin, China.
| | - Xue-Jun Chen
- College of Civil and Architecture Engineering, Guilin University of Technology, Guilin, China; Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering, Guilin, China.
| | - Si-Zhe Yu
- Guangxi Zhuang Autonomous Region Geological Environment Monitoring Station, Guilin, China.
| | - Ru-Long Ban
- College of Civil and Architecture Engineering, Guilin University of Technology, Guilin, China; Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering, Guilin, China.
| | - Xin Yang
- College of Civil and Architecture Engineering, Guilin University of Technology, Guilin, China; Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering, Guilin, China.
| | - Xiaochen Zhang
- College of Civil and Architecture Engineering, Guilin University of Technology, Guilin, China; Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering, Guilin, China.
| | - Yu Han
- Dalian Hongwei Water Conservancy and Hydropower Engineering Company, DaLian, China.
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