On the conditions at failure in schistose rocks

The conditions at failure are examined in schistose rocks using the critical plane approach. A general 3D anisotropic failure criterion is introduced, which accounts for the orientation dependency of strength. The onset of shear cracking is governed by Hoek-Brown's empirical function, while the tensile fracture is monitored by Rankine's cut-off criterion. The directional variation of strength parameters (m, s) in Hoek-Brown criterion, as well …