Experimental Investigation on the Deformability, Ultrasonic Wave Propagation, and Acoustic Emission of Rock Salt Under Triaxial Compression
Experimental Investigation on the Deformability, Ultrasonic Wave Propagation, and Acoustic Emission of Rock Salt Under Triaxial Compression
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DOI：
10.3390/app9040635
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发表时间：
2019-02
期刊：
影响因子：
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通讯作者：
Haoran Li;Zhikai Dong;Zuolin Ouyang;Liu Bo;W. Yuan;Hongwu Yin
中科院分区：
文献类型：
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作者：
Haoran Li;Zhikai Dong;Zuolin Ouyang;Liu Bo;W. Yuan;Hongwu Yin
作为一种主动检测手段的超声波和可以作为被动检测技术的声发射技术，可以从不同的角度揭示岩石的损伤过程。然而，由于实验设备的限制，到目前为止，很少有研究同时采用这两种方法。但同时使用两种方法可以提高实验效率，有助于更全面地了解岩石损伤演化过程。在本研究中，对岩盐进行了单轴压缩下超声波与声发射的联合实验，并测量了其变形特征。断裂过程可分为四个阶段：弹性压缩阶段、裂纹萌生的脆韧转变阶段、损伤萌生的脆韧转变阶段、塑性变形和应变硬化阶段。得到了超声波速、裂纹密度、超声波幅值和衰减系数等参数来评价损伤过程。由于超声波幅值和衰减系数测量的敏感性和可操作性，建议将其作为预测指标。围压对裂纹扩展和声发射活动具有抑制作用，根据声发射活动和能量释放特性定义并确定了损伤极限应力。确定了盐岩的起裂门槛应力、剪胀边界应力、短期强度和损伤极限应力四个临界强度，并对其进行了讨论。这些结果对评价地下盐穴的岩石损伤和指导地下盐穴的运行具有重要意义。
Ultrasonic waves, which constitute an active testing method, and acoustic emissions (AE), which can be applied as passive testing technology, can reveal rock damage processes in different ways. However, few studies so far have simultaneously adopted both, owing to the limitations of the experimental apparatus. However, the simultaneous use of both methods can improve the experimental efficiency and help to understand the rock damage evolution more comprehensively. In this study, concurrent experiments of ultrasonic waves and AE activities were carried out on rock salt under uniaxial compression, and the deformation characteristics were measured. The fracture process was divided into four stages with individual characteristics: the elastic compression stage, brittle-ductile transition with crack initiation, brittle-ductile transition with damage initiation, and plastic deformation and strain hardening stage. The ultrasonic wave velocity, crack density, ultrasonic wave amplitude, and attenuation coefficient were obtained to evaluate the damage process. The ultrasonic wave amplitude and the attenuation coefficient were recommended as forecast indicators, owing to their sensitivity and operability of measurement. The confining pressure had an inhibitory effect on crack expansion and on the AE activity, and the damage ultimate stress was defined and determined according to the AE activity and energy release characteristics. Four critical strengths of the crack initiation threshold stress, dilatancy boundary stress, short-term strength, and damage ultimate stress of rock salt were determined and then discussed. These results are valuable in evaluating rock damage and guiding the operation of underground salt caverns.