Anisotropic deformability and strength of slate from NW-Spain

Slates are metamorphic rocks characterized by the pervasive occurrence of cleavage or foliation producing a highly anisotropic mechanical behavior fissility. Deformability and strength these therefore dependent on plane orientations relative to principal stresses. In this study, failure deformability experimentally investigated means set standard uniaxial triaxial compression tests samples cut with forming different angles. Propagation velocity measurements have also been taken in good number specimens. Compression show that clearly for rock through is observed range dip angles from 15 75°. Transversely isotropic elastic parameters fit based improved existing approaches. Moreover, tested normal parallel relevantly differ, something noted qualitatively past some authors rocks. However, difference has neither explicitly reported case other foliated sedimentary such as shales, nor formalized theoretical The experimental data slates were Jaeger's weakness (JPW) model. Strength criteria differentiating directions proposed adapt JPW model observations slate behavior. Other improvement proposed, use non-linear criterion intact (Hoek-Brown), which shows better represent laboratory results.