Study on the damage and failure characteristics of shale using micro-focus X-ray computed tomography (μ-CT)

In order to figure out the damage and failure characteristics of Longmaxi shale in deformation and failure under loading, three cylindrical specimens were prepared to conduct real- time uniaxial tests. Micro-focus X-ray computed tomography (μ-CT) at different stress levels were used to obtain reconstructed stereograms, and horizontal CT images were obtained for analysis. Based on the scanning results, the initial mineral and pore distribution were extracted and found that they have a combined influence on the compression strength of shale. The cracking evolution were first characterized quantitatively by the changing of pore ratio and crack volume. Moreover, the final crack morphologies were established and the failure degree was assessed by crack volume. The effect of internal mineral and pore evolution on the fracture mode was discussed and showed that the scattered mineral has little effect on the final crack and the increase in pore ratio related to the crack volume.