Simulating fracture propagation in rock and concrete by an augmented virtual internal bond method

This paper develops a practical approach to simulating fracture propagation in rock and concrete based on an augmented virtual internal bond (VIB) method in which the cohesion of solid is modeled as material particles interconnected by a network of randomized virtual micro bonds described by the XuNeedleman potential. The micro bond potential is used to derive macroscale constitutive relations via the CauchyBorn rule. By incorporating different energy contributions due to stretch and shearing, as well as different energy levels under tension and compression of each micro bond, the derived macro constitutive laws are particularly useful for modeling quasi-brittle materials such as rock and concrete which usually have different Poisson ratios and much higher compressive strength than tensile strength. The mesh-size sensitivity associated with strain-softening in the present constitutive model is addressed by adjusting material constants near the crack tip so that the biJ-integral is kept equal to the intrinsic fracture energy of the material. Numerical examples demonstrate that the proposed VIB method is capable of simulating mixed mode fracture propagation in rock and concrete with results in consistency with relevant experimental observations. Copyright (C) 2011 John Wiley & Sons, Ltd.