Generation of strain waves in rock by an explosion in a spherical cavity

A mathematical solution to predict the properties of the strain waves generated when an explosive detonates inside a spherical cavity in an infinite medium is presented. In the case of commercial explosives in rock, the strain pulse is a highly damped oscillating wave train the characteristics of which depend on the properties of the rock (its density, Young's modulus, and Poisson' ratio), on the radius of the cavity, and on the properties of the explosive (its explosion pressure P and the ratio of the specific heats of its explosion gases). The theory is compared with some experimental data; the agreement is fair, if account is taken of charge shape and detonation time effects. Applicability of the theory to prediction of the relative blasting effectiveness of different explosives is briefly discussed.