Discrete fracture in quasi-brittle materials under compressive and tensile stress states

A method for modelling discrete fracture in geomaterials under tensile and compressive stress fields has been developed based on a Mohr-Coulomb failure surface in compression and three independent anisotropic rotating crack models in tension. Extension fracturing is modelled by coupling the softening of the anisotropic rotating crack failure criterion to the compressive plastic strain evolution. Modifications were introduced into an explicit discrete element/finite element code with an explicit Lagrangian contact algorithm to enforce non-penetration of the surfaces created when the tensile strength is depleted. The model is applied to triaxial and plane strain tests, as well as punch tests and borehole breakouts to show that the model is able to quantitatively predict the appropriate load-displacement response of the system in addition to the observed evolution of discrete fracturing in situations comprising a variety of compressive and tensile stress states. (C) 2004 Elsevier B.V. All rights reserved.