Experimental and numerical investigation of the effect of blast-generated free surfaces on blasting vibration

Abstract

In rock blasting, the blast of the former delay always creates new free surfaces for the latter. And the blast-generated free surfaces play a critical role in blasting vibration. A quantitative assessment of the blast-generated free surfaces on blasting vibration was carried out through experimental and numerical studies. Blasting vibration from the first and followed delays in the same row was compared and analysed in two field experiments. A coupled numerical approach with smooth particle hydrodynamics and dynamic finite-element methods was also conducted to simulate the fragmentation process and the blasting vibration from different delays in the same row. The results show that with the increasing number of free surfaces, the peak particle velocity decreases nonlinearly, and if the blasting geometry parameters and charge weight are the same in each blast delay in the same row, the explosive detonated in a first delay always produce higher vibration compared to those followed delays. The charge weight of the first delay in every row should be reduced by certain percentage if the same peak particle velocities are expected from followed delays in the same row.

Keywords:

• blasting
• millisecond-delay
• blast-generated free surface
• vibration
• charge weight per delay

Acknowledgements

Our deepest gratitude goes to the anonymous reviewers for their careful work and thoughtful suggestions that have helped improve this paper substantially.