Effect of the detonation parameters of explosives on the explosion energy distribution of a borehole charge

Abstract

The effect of the detonation parameters of explosives is very pronounced at distances (I-i0)~o (re is the explosive charge radius) in the so-called local zone of the explosion.With increasing distance from the explosion source the effect decreases and, beginning at about 50~o, explosives level out as regards their detonation characteristics.The law of similitude is obeyed; according to this, explosives constitute merely a mass, or to be more exact the product of a mass and the specific heat of the explosion.However, we often need to know the explosion wave parameters specifically in the range (l-10)ro and, more importantly, to predict the explosion energy distribution.The latter determines the mechanism of the explosion work.In this connection it is of interest to assess the effect of the explosive detonation parameters on the explosion energy distribution qualitatively on the basis of an approximate model of the interaction of the system "charge-medlum". Continuing our previous investigations [i], we introduce the conditions of correspondence of explosives and the medium being fractured in terms of the maximum of energy transfer to the wave, and will find an equation determining the maximum wave energy generatable by an explosive with given detonation parameters.Assuming that the wave profile in the medium is H-shaped, the mass of the medium behind the front of a one-dimensional cylindrical wave (1) where Ah is the charge height (this will be taken as i mm for the calculations), Po and p are, respectively, the density of the medium before and after perturbation, re is the initial radius of the explosion cavity of the borehole, and r and R are, respectively, the instantaneous radii of the cavity and the wave front.As the sum of the kinetic and potential energies the shock wave energy is where P and U are, respectively, the pressure and the particle velocity of the perturbed medium.If we assume that the value po/2~ro determines the specific density of the medium at the perimeter before the explosion, and that the corresponding value at the initial moment of the explosion is p~/2~r, the radius at which we first observe fracture of the medium in contact with the layer of explosion products will be called the critical expansion radius