Fracture characteristics and micromechanical theory of rock as a quasibrittle material: Appercu of recent advances

Realistic characterization of rock fracture properties is essential for successful predictions of rock fracture under any situation, including the fragmentation in blasting. The paper presents a review of some interesting recent results on the characterization of rock fracture by point-wise, line-wise and diffuse models for the fracture process zone. The effect of the rate of loading and of crack growth on the fracture characteristics is also reviewed and the micromechanical aspects are discussed. Attention is then focused on the problem of the effect of microcracks on the global stiffness tensor of a microcracked material such as rock, and some new results which take into account the growth of cracks retaining their criticality are described. The lecture is documented by numerical results.