An empirical joint constitutive model (JCM) that
captures the rough wall interaction behaviour of individual
fractures associated with roughness characteristics
observed in laboratory experiments is combined with the
solid mechanical model of the finite-discrete element
method (FEMDEM). The combined JCM-FEMDEM formulation
gives realistic fracture behaviour with respect to
shear strength, normal closure, and shear dilatancy and
includes the recognition of fracture length influence as seen
in experiments. The validity of the numerical model is
demonstrated by a comparison with the experimentally
established empirical solutions. A 2D plane strain geomechanical
simulation is conducted using an outcrop-based
naturally fractured rock model with far-field stresses loaded
in two consecutive phases, i.e. take-up of isotropic
stresses and imposition of two deviatoric stress conditions.
The modelled behaviour of natural fractures in response to
various stress conditions illustrates a range of realistic
behaviour including closure, opening, shearing, dilatancy,
and new crack propagation. With the increase in stress
ratio, significant deformation enhancement occurs in the
vicinity of fracture tips, intersections, and bends, where
large apertures can be generated. The JCM-FEMDEM
model is also compared with conventional approaches that
neglect the scale dependency of joint properties or the
roughness-induced additional frictional resistance. The
results of this paper have important implications for
understanding the geomechanical behaviour of fractured
rocks in various engineering activities