ISSN 1000-3665 CN 11-2202/P
    宋勇军,孟凡栋,毕冉,等. 冻融岩石蠕变特性及孔隙结构演化特征研究[J]. 水文地质工程地质,2023,50(6): 69-79. DOI: 10.16030/j.cnki.issn.1000-3665.202211026
    引用本文: 宋勇军,孟凡栋,毕冉,等. 冻融岩石蠕变特性及孔隙结构演化特征研究[J]. 水文地质工程地质,2023,50(6): 69-79. DOI: 10.16030/j.cnki.issn.1000-3665.202211026
    SONG Yongjun, MENG Fandong, BI Ran, et al. Research on creep characteristics and pore structure evolution characteristics of freezing-thawing rocks[J]. Hydrogeology & Engineering Geology, 2023, 50(6): 69-79. DOI: 10.16030/j.cnki.issn.1000-3665.202211026
    Citation: SONG Yongjun, MENG Fandong, BI Ran, et al. Research on creep characteristics and pore structure evolution characteristics of freezing-thawing rocks[J]. Hydrogeology & Engineering Geology, 2023, 50(6): 69-79. DOI: 10.16030/j.cnki.issn.1000-3665.202211026

    冻融岩石蠕变特性及孔隙结构演化特征研究

    Research on creep characteristics and pore structure evolution characteristics of freezing-thawing rocks

    • 摘要: 寒区露天岩体面临着循环冻融和长期荷载共同作用引起的时效性损伤的考验。为探究寒区环境对岩体稳定性的影响,以陕北某工程的红砂岩为研究对象,从冻融岩石的宏观蠕变特性及细观结构的演化特征着手,通过冻融岩石的加卸载蠕变试验,并配合核磁共振检测,对冻融红砂岩蠕变过程中的宏观力学指标及细观参数的演化进行定量分析。结果表明:应力水平在0.3σucs~0.5σucs时,孔径分布在一个较小范围内波动,当应力水平增高至0.5σucs~0.6σucs时,小孔(横向弛豫时间T2<10 ms)占比下降,大孔(T2>10 ms)占比上升;冻融加剧了蠕变阶段孔隙度的增长,高应力水平下冻融对孔隙度增长的影响更为显著。引入分形理论表征孔隙结构的复杂程度,发现大孔有明显分形特征,而小孔分形特征不明显,总孔分维DT与孔隙度呈正相关;孔隙结构的复杂程度仅在孔隙度较大时才明显影响岩石的蠕变力学特性。建立了有关冻融作用影响及蠕变损伤的冻融-损伤蠕变模型,模型曲线可以很好地反映冻融岩石的蠕变破坏特征,且与试验曲线吻合良好。本研究可为冻融环境下的岩体工程建设提供理论依据。

       

      Abstract: The rock mass of open pit in cold regions is often affected by freezing-thawing cycles and long-term loads. In order to explore the influence of cold region environment on the stability of rock mass, the red sandstone of a project in northern Shaanxi is taken as the research object, starting with the macroscopic creep characteristics and meso-structure evolution characteristics of freezing-thawing rocks. The evolution of macro-mechanical indexes and meso-parameters during the creep process of freezing-thawing red sandstone is quantitatively analyzed through the loading and unloading creep test of freezing-thawing rock and the NMR detection. The results show that the pore size distribution fluctuates in a small range when the stress level is between 0.3σucs−0.5σucs, and when the stress level increases to 0.5σucs−0.6σucs, the proportion of small holes (T2<10 ms) decreases and the proportion of large holes (T2>10 ms) increases, and freezing-thawing aggravates the increase of porosity in the creep stage, and the effect of freezing and thawing on porosity growth is more significant at high stress levels. The fractal theory is introduced to characterize the complexity of pore structure. It is found that the large pores have obvious fractal characteristics, while the fractal characteristics of small pores are not obvious. The total pore fractal dimension DT is positively correlated with porosity. The complexity of pore structure only affects the creep mechanical properties of rock when the porosity is large. The freezing-thawing-damage creep model of freezing-thawing effect and creep damage is established. The model curve can well reflect the creep characteristics of the freezing-thawing rock, which is in good agreement with the experimental curve. This study can provide a theoretical basis for rock engineering construction in freezig-thawing environment.

       

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