A physical basis for determining the specific consumption of explosives

Summary

• 1. The new theory of rock fracture by an explosion, which allows for the various forms of a rock's resistance to the effect of the explosion, has now reached the stage of development when it can be used for solving many practical blasting problems.

• 2. The new theory enables us to make a physical interpretation of the process; it also helps us to analyze the individual phenomena of the very complex process of rock breaking, particularly the way the specific consumption of explosives changes with the blasting conditions.

• 3. The specific consumption of explosives varies not with the charge insertion depth only (as erroneously supposed by G. Lares and others); the change in this consumption differs for different rocks and it depends on the rock's hardness and viscosity (it increases with the hardness). The physical explanation of this is as follows: the consumption of explosives to overcome gravity remains constant, while that for overcoming the rock's cohesion over the break-away area and for crushing differs for different rocks and decreases with the charge's depth.

• 4. It is recommended that the specific consumption of explosives (for ammonite No. 6) be determined from Eq. (11), which takes account of the rock's physicomechanical properties (hardness, viscosity and weight density), the insertion depth of the charge, and the coefficient of utilization of the charge's energy.