Strength anisotropy of shales deformed under uppermost crustal conditions

Conventional triaxial tests were performed on three sets of samples of Tournemire shale along different orientations relative to bedding (0°, 45°, and 90°). Experiments were carried out up to failure at increasing confining pressures ranging from 2.5 to 160 MPa, at strain rates ranging between 3 × 10 −7 s −1 and 3 × 10 −5 s −1 . This allowed us to determine the entire anisotropic elastic compliance matrix as a function of confining pressure....