Comparative Study on Mineral-Scale Microcrack Propagation of Shale under Different Loading Methods

Figure 8

In loading method I (tensile loading) and loading method IV (shear loading), the strain and microfracture before the formation of macro-cracks. (a, b) Strain contour before macro-crack formation in loading methods I and IV, respectively. (c, d) In loading methods I and IV, the AE location of the microcracks distributed in the rock before the macrocrack formed. Red dots are the AE location of tensile fractures, purple dots are the AE location of shear fractures, and the colors between the two are the AE location of tensile-shear fractures. The size of the dot represents the level of AE energy. The AE energy of microfracture before the macrocrack formed is relatively small, so the AE energy magnification of this figure is larger than the others in this paper.

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