Stress Waves and Dynamic Characteristics of Rocks under Detonator's Attack

Abstract

The experiments have been carried out to investigate the characteristics of the stress waves induced in rocks when they are attacked by an explosion of a detonator and also to study some mechanical properties of rocks under such an impulsive load. To obtain the shape of a stress wave which is induced in a cylindrical bar specimen by an impulsive load, a method utilizing the displacement of the free end face of the specimen was used in this study and it was recognized that this method was simpler and more convenient than the pellet method developed by J. S. Rinehart. The change in the propagation velocity of the stress wave with distance from the shot point was studied in detail and it was found that even in the case of detonator's attack a plastic wave or a shock wave seemed to be generated in the limited region near the shot point. The dynamic stress-strain relationship and the dynamic strengths for compression and tension were determined for three kinds of rock specimens and these results were compared with those obtained by the conventional static test.