In present blasting practice in mining and civil engineering, solid charges (completely filled charge chambers) are used both to break rock when maximum crushing action is required and for ejection blasting when the mining effect must be a maximum; i.e., two essentially different types of operation are effected with the aid of the same charges.The use of present explosives with traditional methods of blasting involves marked overcrushing of the rock in the zone adjacent to the charge, which simultaneously becomes a region of strong absorption of energy. These heavy energy losses in the initial stage of the blast cannot be compensated later, because the transmission of energy in the explosion of a solid charge is practically instantaneous.Thus the use of solid charges to crush rock is inefficient both from the viewpoint of the mechanics of crushing and from the viewpoint of the occurrence of heavy energy losses due to the irrational mechanism of transfer of the energy of the blast to the surrounding medium.With the aim of altering the mechanism of action of the blast and the efficient transfer of its energy to the solid medium, N. V. MeUnikov proposed the idea that the energy of the blast might be redistributed and a reduction might be made in the losses on inefficient forms of work in crushing the rocks [1].The essence of this idea is that by reducing the initial pressure in the detonation products and increasing the duration of their action on the rock one might reduce the dissipative losses in the zone near the charge, thus reducing the possibility of overcrushing of the rock but increasing the amount of energy transmitted to the medium. This idea simultaneously involves a change in the actual mechanism of fracture of the rock by increasing the dynamics of the crushing process by using interference of the shock waves and interaction of the gas currents. This is realized in practice by making charges with air gaps for rock crushing and charges with air cavities for ejection blasting [2]. Thus, for the first time it has been shown that by changing the mechanism of transfer of the energy of the blast to the solid medium we can change the fundamental form of the work which must be done by the explosion.Although charges with air gaps to improve rock crushing and charges with air cavities to increase the efficiency of ejection blasting have the common idea of redistribution of the energy of the explosion, we must note that they differ in principle both in the mechanism of action and in the construction of the charges.For rock crushing it is necessary that the main compression wave have an amplitude exceeding the strength of the rock. Therefore the charge in the blast hole must be pressed tightly against the rock without any radial gaps. In this case the pressure of the detonation products can be reduced only with the aid of air gaps between separate parts of the charge along its axis. During the first stage of development of the explosion these air gaps form a kind of energy accumulator, which first stores and then e...
