Effects of confining pressure on crater blasting in rock-like materials under electric explosion load

摘要

The knowledge of crater blasting in rock under confining pressure is essential to excavation design of deep underground engineering works. By using an electric explosion method, experiments on crater blasting of rock-like specimens under conditions of no confining pressure and uniaxial confining pressure were performed. The cracking processes on the surface of the specimen were observed by an ultra-high speed camera. Moreover, changes in the shape and size of a crater with confining pressure were studied. Thereafter, a numerical simulation was undertaken to assess damage evolution inside the specimen. The research results demonstrated that radial and circular cracks on the surface and radial and spalling cracks inside the specimen dominated the fracturing of the specimen. Propagation of these cracks was influenced by confining pressure. Without confining pressure, the crater was approximately circular, while it was similar to an ellipse under vertical confining pressure. The greater the confining pressure, the greater the volume, opening angle, and perimeter of the crater. The findings of this investigation provide certain support for the arrangement of blasting holes in excavation of deep geological engineering.