This study reports on the Heaviside‐based digital image correlation (H‐DIC) procedure and its application in fracture analysis. This improved DIC procedure was proposed to solve the uncertainty problems at the vicinity of the crack and to evaluate the opening and shear movements of crack lips and the orientations of cracks in the subset. Some tests were conducted to demonstrate the performance of the H‐DIC algorithm. An application on argillaceous rock mass exhibiting multiple mixed‐mode fractures is shown to validate the efficiency and robustness of the proposed method. This application consisted in processing images acquired from an experimental investigation performed in a gallery front submitted to climatic seasonal variations. The results illustrated how the H‐DIC procedure enables to localise and to quantify the opening, shearing and orientation of subpixel cracks. A sensibility study performed on the opening and shear components demonstrated that the precision of crack aperture by H‐DIC procedure is close to 0.14 pixel and the spatial resolution is equal to one pixel. Moreover, the crack area was calculated from local apertures on a monitoring duration of 1 year, and a maximum value of 595.8 mm² in winter was obtained.

中文翻译：

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基于Heaviside的数字图像相关技术对混合模式裂缝裂纹唇运动的亚像素精度

这项研究报告了基于Heaviside的数字图像相关（H-DIC）程序及其在裂缝分析中的应用。提出了改进的DIC程序，以解决裂纹附近的不确定性问题，并评估裂纹唇的张开和剪切运动以及子集中裂纹的方向。进行了一些测试以证明H‐DIC算法的性能。结果表明，在具有多个混合模式裂缝的泥质岩体上的应用证明了该方法的有效性和鲁棒性。该应用程序包括处理从在画廊前进行的实验研究中获得的图像，这些图像已提交给气候季节性变化。结果说明了H‐DIC程序如何定位和量化开口，亚像素裂纹的剪切和取向。对开口和剪切分量进行的敏感性研究表明，通过H‐DIC程序，裂纹孔径的精度接近0.14像素，空间分辨率等于一个像素。此外，通过在1年的监测持续时间内从局部孔计算出裂纹面积，并且在冬季获得了最大值595.8 mm ²。