Experimental study of ultrasonic wave attenuation across parallel fractures
Experimental study of ultrasonic wave attenuation across parallel fractures
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DOI：
10.1080/17486020600834613
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发表时间：
2006-08
期刊：
影响因子：
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通讯作者：
J. Zhao;J. Cai;X. B. Zhao;H. B. Li
中科院分区：
文献类型：
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作者：
J. Zhao;J. Cai;X. B. Zhao;H. B. Li
裂隙和其他非焊接结构面是岩体重要的力学和水力特征。它们对波传播的影响可以用位移不连续法作为边界条件来模拟。对于小振幅波入射，如超声波，应力波的幅度太小，无法调动非线性裂缝变形，因此在这些研究中采用线性模型来描述裂缝变形行为。蔡家刚，赵家杰（Int.）[j]罗敏，科学。[j] .岩石力学与工程学报，2000,37(4),661-682 .]利用特征方法，通过考虑缝间波反射来检测纵波在线性可变形裂缝上的衰减。在本研究中，进行了一系列的实验室试验来验证蔡和赵得到的理论解。这些测试包括铝试样的超声波测试（校准测试）、完整水泥砂浆试样、单断裂试样和双断裂试样。在不同静应力条件下，超声波在水泥砂浆人工裂缝中正常传播。传输的脉冲被捕获，随后与理论预测进行比较。总体而言，实验结果与理论预测吻合较好。此外，实验研究还为波在不连续面上的传播提供了进一步的认识（例如位移不连续面方法在动力问题中的适用性）。
Fractures and other non-welded discontinuities are important mechanical and hydraulic features of rock masses. Their effect on wave propagation can be modelled as a boundary condition by displacement discontinuity methods. For small-amplitude wave incidence, such as an ultrasonic waves, the magnitude of the stress wave is too small to mobilize non-linear fracture deformation, and so linear models are adopted in these studies to describe fracture deformational behaviour. J.G. Cai and J. Zhao (Int. J. Rock Min, Sci., 2000, 37(4), 661–682.) used the method of characteristics to examine P-wave attenuation across linear deformable fractures by considering interfracture wave reflections. In the present study, a series of laboratory tests were carried out to verify the theoretical solutions obtained by Cai and Zhao. These included ultrasonic tests across an aluminium specimen (calibration tests), intact cement mortar specimens, single-fracture specimens, and two-fracture specimens. During the tests, ultrasonic waves propagate normally across artificial fractures cast by cement mortar under different static stresses. Transmitted pulses are captured and subsequently are compared with the theoretical predictions. Generally, the experimental results agreed well with the theoretical predictions. In addition, the experimental study also provided further understanding of wave propagation across discontinuities (e.g. the applicability of displacement discontinuity methods in the dynamic problems).