NUMERICAL-SIMULATION OF FRACTURE SET FORMATION - A FRACTURE-MECHANICSMODEL CONSISTENT WITH EXPERIMENTAL-OBSERVATIONS

A physically based model for the evolution of a single set of planar, parallel fractures subject to a constant remote stress is presented. T he model simulates the mechanical interaction between fractures using a recently developed approximation technique for stress analysis in el astic solids with many fractures. A comparison between experimental an d numerical results shows that the model can accurately simulate the d evelopment of experimentally generated fracture sets. Once the flaw ge ometry is specified, only one parameter controls the geometric evoluti on of the fracture set. This parameter, the velocity exponent, relates fracture propagation velocity to stress concentration at the fracture tip. Monte Carlo sensitivity analyses suggest that this parameter als o controls the extent to which fracture growth is concentrated within zones or clusters. Similar analyses suggest that the extent of fractur e clustering is less sensitive to the flaw density.