Cracking Evolution and Failure Characteristics of Longmaxi Shale Under Uniaxial Compression Using Real-Time Computed Tomography Scanning

To determine the cracking and failure characteristics of Longmaxi shale in deformation and failure under loading, cylindrical specimens were prepared to conduct a series of uniaxial compression tests. Real-time computed tomography (CT) at different stress levels were used to obtain reconstructed stereograms, and horizontal CT images and vertical slices were obtained for analysis. Based on the CT images and slices, the cracking evolution of Longmaxi shale in the horizontal and vertical direction was determined qualitatively, the quantitative distributions of crack area during the loading were revealed and the variation in crack volume at different stress levels was first obtained. Based on the grey histogram of the reconstructed three-dimensional volume, the initial mineral distribution, internal pore evolution and final crack morphologies and volumes were established and their inter-relationship was discussed. These qualitative and quantitative results are necessary to characterize and understand the cracking evolution and failure characteristics of the Longmaxi shale.