A note on Velocity of Detonation (VOD)

Given that the VOD is the only measurable magnitude related to an explosive that can be given a number with certainty, it is easy to comprehend why it has been overemphasized as an indication of explosive strength. VOD is a function of the explosive configuration, hole diameter and confinement. Hole diameter and confinement are generic environment variables for any given blast. The same explosive in different environments will manifest different VODs. In their literature, manufacturers usually quote the unconfined VOD of a small sample of explosive in a small diameter. Rather than strength, VOD gives a relative indication of the energy partitioning between shock and heave. The higher the VOD, the higher the shock component in relation to the total energy. While low VOD explosives will shift the energy partition towards a higher proportion of heave. In any case, the VOD would have to be measured in a real borehole situation in order to be meaningful. In-hole VOD measurements differ greatly from the values quoted in standard literature.