Modern drilling and blasting work comprises a wide range of processes, based on rock breaking by shock waves, stress waves, waves of rarefaction, and explosion products created by detonating explosive charges. The mechanical effect of an explosion on the ambient medium evidently depends both on the detonation characteristics of the explosives and on the properties of the medium (rock). Therefore, to find ways of increasing the efficiency of existing blasting methods, explosives, and shotfiring, importance attaches to a detailed investigation of detonation procedures for commercial explosives, of the properties of rocks, and of the mechanism of their fracture by an explosion.The experiments were performed on cylindrical ammonite 6ZhV charges, made in the factory (batch 1) or laboratory (batch 2). We used mainly the former, in the form employed by the ore mining industry. The procedure, technique, methods, and limiting conditions of the experiment are described in [1][2][3][4][5][6][7][8][9][10]. The accuracy of a mass velocfty determination was ~3%, the accuracy of the time measurements ~ 10-15q0. Table 1 gives the results of an experimental determination of the ammonite 6ZhV detonation parameters (1 and 2 denote factory and laboratory products, respectively, and ,o denotes data obtained by extrapolating the dependences of D and U 1 on the reciprocal of the diameter k 1/d = 0). Table 2 gives the time dependences of the mass velocity after the break, characterizing the profile of the expansion wave in 6ZhV factory charges. The time was calculated from the shock front. The values in Tables 1 and 2 are the means of three or four experiments.It will be seen from Table 1 that for all the investigated charge densities, U 1 and P, increase with the diameter, but the time and width of the chemical reaction zone decrease. The polytrope index of the explosion product also decreases, despite the increase in pressure. Thus in the case of ammonite 6ZhV, the changes in the detonation parameters with increasing charge diameter at constant density are qualitatively similar to those of other explosives [21.At low charge diameters (~ 40 ram), irrespective of the dependence on density, the detonation parameters (D, Ul, and P~) are far below the ideal values. This means that part of the energy of the explosives is not transferred to the detonation wave (up to the Chapman-Zhuge surface); it is perfectly likely that it is evolved as an expansion wave and plays a specific part in fracturing of the rock, but there is also the possibility that it is not evolved due to rapid cooling and chilling of the explosives.The decrease in the detonation parameters in charges of finite diameter in comparison with their ideal values depends not only on the charge diameter, but also on the batch of the product. Figure 1 is a plot of Pt versus the charge diameter for two batches of ammonite 6ZhV with P0 = 1.0 g/cm s. At low charge diameters (20-60 ram) the P~ of laboratory 6ZhV (curve 2) is much higher than for factory charges. These differences apparen...

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In this article we continue the series of investigations begun in [1,2]. All the experiments were performed on cylindrical charges of diameter 80-300 mrr~ The chargelength was usually three or four times the diameter; with a fairly powerful initiator (100-200 g of ammonite No. 6 or TNT). this enabled us to determine the detonation parameters under steady conditions. In certain cases (at virtually critical charge diameters) we used charges of various lengths in order to determine the steadiness of the explosion processes and to refine the values of the crRieal diameters.The charges were prepared by sprinkling the usual amount of explosives into thin cardboard sheaths. The 9 charging density was 1.0 g/em s. As the work progressed, it was necessary to use different batches of explosives.The experimental results exhibited marked scatter at virtually critical charge diameters. In this connection, we performed special experiments on the propagation of explosion processes in relation to the batch of explosive and its moisture content, which enabled us to assess the possible effect of random factors on the detonation parameters (caldng, wetting, etc.) which may come into play during practical use of explosives.