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<p>In order to find out the deterioration rule and microscopic damage mechanism of the moraine on the Qinghai-Tibet Plateau under the freeze-thaw (F-T) cycle, F-T tests were carried out on the moraine samples with an initial water content of 10.7%. The freezing temperature was − 16&#xa0;°C and the thawing temperature was 28&#xa0;°C. The standard triaxial consolidation undrained (CU) tests were carried out under three confining pressures (2, 10, 20&#xa0;kPa). The method based on discrete element theory was proposed to simulate the triaxial compression tests and F-T damage of water particle expansion. The results show that: (1) in the process of F-T, micro-cracks appeared in the surrounding areas and gradually expanded to the middle, in which the tensile micro-cracks occupied dominant position. In the early F-T stage (2–5 times), horizontal compression was the main factor among the particles, and a large number of tensile micro-cracks with a tendency of 90° were developed. (2) soil cohesion (c) decreased by a negative exponential function with the increase of F-T times N and decreased by 40% at the initial F-T stage (2–5 times), while the internal friction angle (φ) fluctuated slightly. (3) according to the characteristics of the fracture evolution, the stress-strain curve of the loading processes were divided into four deformation stages. The specimen with 20&#xa0;F-T cycles were more severely damaged when loaded and formed distinct shear bands, micro-cracks deceleration gradient transition point B can be used as a “precursor feature” in the processes of micro-cracks extension-penetration-formation damage. The study provides theoretical support and parameter guidance for the prevention and reduction of glacial lake outburst disaster and promotes the coordinated development of human-land relationship regional system in the Qinghai-Tibet Plateau.</p>

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The study of microscopic damage in moraine soils under freeze-thaw cycles based on discrete element

  • 期刊论文

  • 发表日期：

    2025年10月30日

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  • Li Mingli,
  • Liu Jianuo,
  • Jiang Yuanjun,
  • Chang Ming,
  • Zheng Haijun,
  • Tian Hongling,
  • Huang Shibo

摘要

In order to find out the deterioration rule and microscopic damage mechanism of the moraine on the Qinghai-Tibet Plateau under the freeze-thaw (F-T) cycle, F-T tests were carried out on the moraine samples with an initial water content of 10.7%. The freezing temperature was − 16 °C and the thawing temperature was 28 °C. The standard triaxial consolidation undrained (CU) tests were carried out under three confining pressures (2, 10, 20 kPa). The method based on discrete element theory was proposed to simulate the triaxial compression tests and F-T damage of water particle expansion. The results show that: (1) in the process of F-T, micro-cracks appeared in the surrounding areas and gradually expanded to the middle, in which the tensile micro-cracks occupied dominant position. In the early F-T stage (2–5 times), horizontal compression was the main factor among the particles, and a large number of tensile micro-cracks with a tendency of 90° were developed. (2) soil cohesion (c) decreased by a negative exponential function with the increase of F-T times N and decreased by 40% at the initial F-T stage (2–5 times), while the internal friction angle (φ) fluctuated slightly. (3) according to the characteristics of the fracture evolution, the stress-strain curve of the loading processes were divided into four deformation stages. The specimen with 20 F-T cycles were more severely damaged when loaded and formed distinct shear bands, micro-cracks deceleration gradient transition point B can be used as a “precursor feature” in the processes of micro-cracks extension-penetration-formation damage. The study provides theoretical support and parameter guidance for the prevention and reduction of glacial lake outburst disaster and promotes the coordinated development of human-land relationship regional system in the Qinghai-Tibet Plateau.