潘振兴,杨更社,叶万军,等. 2020.干湿循环作用下原状黄土力学性质及细观损伤研究[J].工程地质学报,28(6):1186-1192. doi:10.13544/j.cnki.jeg.2019-423. DOI: 10.13544/j.cnki.jeg.2019-423
    引用本文: 潘振兴,杨更社,叶万军,等. 2020.干湿循环作用下原状黄土力学性质及细观损伤研究[J].工程地质学报,28(6):1186-1192. doi:10.13544/j.cnki.jeg.2019-423. DOI: 10.13544/j.cnki.jeg.2019-423
    Pan Zhenxing, Yang Gengshe, Ye Wanjun, et al. 2020. Study on mechanical properties and microscopic damage of undisturbed loess under dry and wet cycles[J]. Journal of Engineering Geology, 28(6): 1186-1192. doi: 10.13544/j.cnki.jeg.2019-423.
    Citation: Pan Zhenxing, Yang Gengshe, Ye Wanjun, et al. 2020. Study on mechanical properties and microscopic damage of undisturbed loess under dry and wet cycles[J]. Journal of Engineering Geology, 28(6): 1186-1192. doi: 10.13544/j.cnki.jeg.2019-423.

    干湿循环作用下原状黄土力学性质及细观损伤研究

    STUDY ON MECHANICAL PROPERTIES AND MICROSCOPIC DAMAGE OF UNDISTURBED LOESS UNDER DRY AND WET CYCLES

    • 摘要: 增湿-减湿循环作用是黄土地区工程发生病害的主要原因之一,探究增湿-减湿循环对黄土体结构损伤机理有重要的理论和工程意义。本文以延安地区的黄土为研究对象,开展不同含水率、不同次数的原状黄土增湿-减湿循环试验,分析干湿循环诱发黄土孔隙率、抗剪强度及其参数的变化规律,同时使用核磁共振技术获取黄土内部裂隙发展的损伤演化。结果表明:随着干湿循环次数的增多,土体呈现出孔隙率逐渐增大、液限和塑性指数相继减小、塑限基本不变的规律,究其原因是内部颗粒的集、散动态变化引发了黄土损伤;干湿循环次数和含水率的增加弱化了土体颗粒的胶结作用,使得抗剪强度、黏聚力和内摩擦角降低,当试样含水率超过塑限后下降趋势更加明显;黄土历经核磁共振表明,试样内部小于0.025 μm的微孔隙随着干湿循环次数的增加逐渐向0.025~0.63 μm的小孔隙组过渡,同时新生孔隙开始产生。

       

      Abstract: Humidification-dehumidification cycle is one of the main causes of engineering diseases in the loess area. It is of great theoretical and engineering significance to explore the mechanism of the humidification-dehumidification cycle to damage the loess structure. In this paper, the loess in Yan'an area is taken as the research object. The undisturbed loess humidification-dehumidification cycle tests with different water contents and different times are carried out to analyze the change rules of porosity, shear strength and parameters of loess induced by dry and wet cycles. NMR technology is used to obtain the damage evolution of crack development in loess. The results show that with the increase of the times of dry-wet cycling, the soil exhibits a gradual increase in porosity, a decrease in the liquid limit and plasticity index, and a basically constant plastic limit. The reason is the dynamic changes in the internal particles loess damage. The increase of dry-wet cycling times and water content weakens the cementation of the soil particles, which reduces the shear strength, cohesion, and internal friction angle. When the water content of the sample exceeds the plastic limit, the decline becomes more obvious. The NMR of the loess shows that with the increase of the times of dry-wet cycling, micropores smaller than 0.025 μm inside the sample gradually transits to small pore groups of 0.025~0.63 μm and new pores begin to occur.

       

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