Meso-structure Analysis on Instability of Dynamic Fracture in Rock

摘要

On the basis of three point bending dynamic fracture tests with high speed photography, the fracture surfaces are scanned by Scanning Electronic Microscope(SEM)and Laser Profilometer. Instability in rapid rupture of rocks is analyzed from the phenomena that occur in those meso-structures. From energy point of view, the instability mechanism concerning microbranching and fracture mode dependence of crack velocity is discussed. As a result of instability, the critical dynamic fracture energy is an increasing function of crack velocity, rather than a constant material parameter.