杨国生, 左双英, 莫云川, 等. 2021.基于核磁共振技术的贵阳红黏土剪切全过程孔隙演变规律研究[J].工程地质学报, 29(5): 1320-1330. doi: 10.13544/j.cnki.jeg.2021-0499.
    引用本文: 杨国生, 左双英, 莫云川, 等. 2021.基于核磁共振技术的贵阳红黏土剪切全过程孔隙演变规律研究[J].工程地质学报, 29(5): 1320-1330. doi: 10.13544/j.cnki.jeg.2021-0499.
    YANG Guosheng, Zuo Shuangying, MO Yunchuan, et al. 2021. NMR technology based study on pore evolution pattern of guiyang red clay shear whole process[J]. Journal of Engineering Geology, 29(5): 1320-1330. doi: 10.13544/j.cnki.jeg.2021-0499.
    Citation: YANG Guosheng, Zuo Shuangying, MO Yunchuan, et al. 2021. NMR technology based study on pore evolution pattern of guiyang red clay shear whole process[J]. Journal of Engineering Geology, 29(5): 1320-1330. doi: 10.13544/j.cnki.jeg.2021-0499.

    基于核磁共振技术的贵阳红黏土剪切全过程孔隙演变规律研究

    NMR TECHNOLOGY BASED STUDY ON PORE EVOLUTION PATTERN OF GUIYANG RED CLAY SHEAR WHOLE PROCESS

    • 摘要: 为研究常规三轴压缩条件下贵阳红黏土剪切全过程孔隙结构的演化规律,探讨分析贵阳红黏土细-微观结构形态变化,揭示贵阳红黏土宏观破坏形态与细-微观结构变化的关联性。采用全自动三轴仪、低场核磁共振技术以及SEM扫描电镜对贵阳红黏土开展全过程剪切测试,并结合颗粒(孔隙)及裂隙图像识别与分析系统(PCAS)对剪切前后的试样进行分析。研究结果表明:贵阳红黏土T2谱图呈现出3种峰型,分别对应大孔隙、中孔隙以及小孔隙;荷载作用下贵阳红黏土试样的变形破坏主要以内部颗粒之间相对位置的调整为主,孔隙体积整体表现为减小;随着应力的增加,红黏土逐渐形成肉眼可见的弧形小褶皱,大尺度孔隙逐渐向小尺度的孔隙发展,小孔隙数量逐渐增加,大-中孔隙数量逐渐减少,孔隙方向越来越混乱;当小褶皱逐渐扩展、贯通形成大的滑移面,孔隙形态表现出短暂的方向性,之后滑移面的压密将使小孔隙数量减少,大-中孔隙数量增加;在整个剪切过程中,贵阳红黏土孔隙形态逐渐趋于相似,孔隙边界趋于复杂。

       

      Abstract: This paper studies the evolution of pore structure of Guiyang red clay during the whole process of shearing under conventional triaxial compression conditions, explores and analyzes the changes of fine-microstructure morphology of Guiyang red clay, and reveals the correlation between macroscopic damage morphology and fine-microstructure changes of Guiyang red clay. A fully automatic triaxial instrument, low-field NMR technique and SEM scanning electron microscope are used to conduct the whole process shear test on Guiyang red clay, and to analyze the specimens before and after shear by combining with the Particles(Pores) and Cracks Analysis System(PCAS).The research results show that the T2 spectrum of Guiyang red clay shows three types of peaks, corresponding to large pores, medium pores and small pores. The deformation and damage of Guiyang red clay specimens under the action of load are mainly based on the adjustment of the relative position between internal particles. The pore volume shows an overall decrease. With the intensification of stress, the red clay gradually forms small folds visible to the naked eye, the large scale pores gradually develop into small scale pores, the number of small pores gradually increases, the number of large-medium pores gradually decreases, and the pore direction becomes more and more confused. When the small folds gradually expand and penetrate to form a large slip surface, the pore morphology shows transient directionality. Afterward the compression of the slip surface can reduce the number of small pores and increase the number of large-medium pores. During the whole shearing process, the pore morphology of Guiyang red clay gradually tends to be similar and the pore boundary tends to be complex.

       

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