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Chaoqun Chu, Shunchuan Wu, Chaojun Zhang, and Yongle Zhang, Microscopic damage evolution of anisotropic rocks under indirect tensile conditions: Insights from acoustic emission and digital image correlation techniques, Int. J. Miner. Metall. Mater., 30(2023), No. 9, pp.1680-1691. https://dx.doi.org/10.1007/s12613-023-2649-y
Chaoqun Chu, Shunchuan Wu, Chaojun Zhang, and Yongle Zhang, Microscopic damage evolution of anisotropic rocks under indirect tensile conditions: Insights from acoustic emission and digital image correlation techniques, Int. J. Miner. Metall. Mater., 30(2023), No. 9, pp.1680-1691. https://dx.doi.org/10.1007/s12613-023-2649-y
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间接拉伸条件下各向异性岩石的微观损伤演化:基于声发射和数字图像相关技术的见解

摘要: 岩石层理结构引起的各向异性通常表现在岩石的力学行为和破裂模式中。本研究对七组页岩圆盘试样进行巴西试验,试样具有不同的层理角度。采用声发射(AE)和数字图像相关(DIC)技术监测试样的实验室原位破坏过程。此外,通过扫描电子显微镜(SEM)观察受损试样的裂纹形态。结果揭示了页岩的拉伸力学行为与结构依赖性。在试验的初期,页岩圆盘在不同位置和试验时间下呈现压缩现象。随着层理角度的增加,压缩区域的位置向下移动并逐渐消失。宏观破裂的位置特征通过AE事件定位结果得到很好的描述,而主导频率分布与层理角度相关,同时,发现b值存在应力依赖性。层间裂纹转向角和穿过层理的裂纹数量随着层理角度的增加而增加,表明裂纹发育之间存在竞争。SEM结果揭示试样的破裂模式可以分为三类:沿层理的拉伸破裂与基质的剪切破裂,沿层理的剪切破裂与基质的拉伸破裂混合阶梯破裂模式,以及沿多个层理的剪切破裂与基质的拉伸破裂混合破裂模式。

 

Microscopic damage evolution of anisotropic rocks under indirect tensile conditions: Insights from acoustic emission and digital image correlation techniques

Abstract: The anisotropy induced by rock bedding structures is usually manifested in the mechanical behaviors and failure modes of rocks. Brazilian tests are conducted for seven groups of shale specimens featuring different bedding angles. Acoustic emission (AE) and digital image correlation (DIC) technologies are used to monitor the in-situ failure of the specimens. Furthermore, the crack morphology of damaged samples is observed through scanning electron microscopy (SEM). Results reveal the structural dependence on the tensile mechanical behavior of shales. The shale disk exhibits compression in the early stage of the experiment with varying locations and durations. The location of the compression area moves downward and gradually disappears when the bedding angle increases. The macroscopic failure is well characterized by AE event location results, and the dominant frequency distribution is related to the bedding angle. The b-value is found to be stress-dependent. The crack turning angle between layers and the number of cracks crossing the bedding both increase with the bedding angle, indicating competition between crack propagations. SEM results revealed that the failure modes of the samples can be classified into three types: tensile failure along beddings with shear failure of the matrix, ladder shear failure along beddings with tensile failure of the matrix, and shear failure along multiple beddings with tensile failure of the matrix.

 

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