Explosion wave and explosion fracture characteristics of cylindrical charges

Abstract

The distribution characteristics of the explosion wave field of a cylindrical charge were investigated in this paper via a high-speed schlieren experiment. Based on the fractal theory, the paper studies the crack propagation characteristics of the media under the action of the cylindrical charge explosion impact at different initiation points. The results show that the velocity of detonation appeared attenuation region when the detonation wave changes to the shock wave, and a certain angle of detonation wave ranging from 580to 62°. Based on the schlieren experiment and the theoretical model, the included angle between the explosion wave in the vicinity of the detonation point and the blasthole wall surface is about 90°, during a stable explosion, the ultimate included angle between the explosion wave and the blasthole wall surface is about 60°. Based on the analysis of the propagation characteristics of the explosion cracks of the cylindrical charge, the angle of incident makes the initiation and propagation of the cracks around the blasthole deflect and the angle of deflection coincides with the theoretical calculation value. The pulverization zone formed in the vicinity of the detonation point is larger than in other zones, but the crack zone is smaller than in other zones. Moreover, the cracking range produced by the cylindrical charge is roughly the range of its five-fold blasthole diameter. There were significant fractal characteristics, within the range of one-to two-fold blasthole diameter, the medium is completely pulverized and forms a zone of dense cracks; within the range of three-to four-fold blasthole diameter, the medium is severely damaged and a crack transition zone forms; five-fold blasthole diameter, there are a few explosion cracks in the medium and a zone of sparse cracks forms.