A new discrete fracture modelling approach for rock masses

Abstract

A method for modelling discrete fracture in rock masses under tensile and compressive stress fields is presented, 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. An explicitly time-integrated coupled discrete element/finite element approach is employed with an explicit Lagrangian contact algorithm to enforce non-penetration of the surfaces created when the tensile strength is depleted. The geomechanical model is applied to naturally fractured rock masses, which are characterised by field mapping and borehole data integrated in a stochastic 3D discrete fracture network model. This approach maximises the utility of the field data and provides a direct approach to the determination of rock mass strength and deformability. It also provides a realistic insight into complex failure mechanisms. Typical applications are mine pillars, roofs, hangingwalls and block caving. The model has also been used on rock slopes.