Numerical simulation of fabric-guided micro-fracturing in rock by using
3D Voronoi tessellation
E. Ghazvinian & M. Diederichs
GeoEngineering Centre, Queen’s University, Kingston, ON, Canada
e.ghazvinian@queensu.ca, diederim@queensu.ca
ABSTRACT: Many rocks near the earth’s surface represent anisotropic properties due to bedding,
stratification, layering, foliation, fissuring or jointing that form a fabric in the rock. The effect of
anisotropy on the elastic properties and strength of rock is well understood however the effect of
anisotropy on the onset of crack initiation and crack propagation thresholds remains a challenge for the
researchers. Numerical methods with the ability to simulate crack damage progression in rock by direct
simulation of crack initiation and propagation will be prominent for better understanding of microfracturing behaviour of foliated/laminated rocks.
A new methodology has been developed for simulation of crack damage progression in anisotropic rock
by using 3D Voronoi tessellation in 3DEC. In this method elongated Voronoi grains will be used to
represent layering in the rock. The available data for calibration and validation of generated models are
made available from Uniaxial Compressive Strength (UCS) testing of the Cobourg limestone specimens
with different orientations (0, 30, 45, 60 and 90 degrees) with respect to bedding. Two of the tested
samples will be used for model calibration (joint properties that act as the bonding between grains) and
the rest for validations of the simulation results.
To numerically investigate the existence of fabric-guided fracturing phenomenon and its effect on crack
damage thresholds a new modelling approach is proposed. In addition to a better understanding of
micro-mechanics behind the interaction of stress induced micro-cracks with the available fabric in the
rock, numerical modelling of micro-fracturing in foliated/laminated rock can also be extended to a larger
scale to simulate structurally controlled brittle spalling around deep underground excavations.
KEYWORDS: Crack initiation, crack propagation, anisotropy, fabric-guided fracturing, Voronoi
tessellation.