LAUSR

Abstract Since most geological contacts in Earth's crust represent potential sites of interface cracks, these cracks are of particular importance in geological engineering. Fracture propagation of interface cracks growth between dissimilar rock layers depends on the contrasting elastic properties across the bedding interface. Most of the topics associated with interfaces in rock mechanics and geological engineering have focused on the reciprocal influence between ordinary cracks and layer surfaces without taking into account the presence of interfacial flaws between rock layers. In this research, the case of an inclined internal interface crack between two dissimilar rock layers under compression and tension was studied in detail. The effect of crack inclination angle on the stress intensity factor and on the stress distribution functions in the vicinity of an interface crack tip was investigated. Our results indicated that interface crack growth can occur in stiffer or more compliant layer depending on the elastic stiffness contrast (differences in Young's Modulus between two layers of rock) and crack inclination angle. The critical value of crack inclination angle, after which interface crack growth can occur in one of two dissimilar rock layers, was determined by taking into account the elastic stiffness contrast and Poisson's ratio of rock formations. Fracture envelopes for the heterogeneous rock medium are located above those of the homogeneous rock medium and by increasing the elastic stiffness contrast of dissimilar rock layers, the area under fracture envelope increases and the interface cracks needs more energy to satisfy fracture condition.