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Triaxial compression tests are conducted on Longmaxi shale under high temperature and high confining pressure condition corresponding to a depth of 3000 m for two typical bedding plane orientations (0° and 90°). It is found that the crack initiation stresses and crack damage stresses of the Longmaxi shale specimens with different vein orientations are different, reflecting that the inclination of the bedding plane has a non-negligible influence on the microcrack initiation and propagation. In addition, the brittleness index of the Longmaxi shale with a bedding plane orientation of 90° is greater than that with an orientation of 0°, which confirmed that the brittleness index is related to the structural orientation under a high temperature and high confining pressure condition. Concerning the failure patterns, both the shear and tensile fracture modes has been observed.

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