爆破による岩石破壊のメカニズムについて

抄録

It is well known that the external effects of a detonating explosives are of two elements in a rock blasting due in the first place to the shock wave and in the second place to the expansion of the detonation products. In the case of confined charged blasting, which of these two elements could be the main part of the effective energy required for complete loosing of the rock?
It is not solved yet experimentally, because of many difficulties and restricts in experiment with explosive, depending on its rapidity of reaction, enormous pressure and high temperature.
So until now, the large number of researchers had made an experiment in such a way that they gave the whole energy of these two elements to the rock at a time, trying to put an end to the arguments.
But here we took the new method for our experiments that could give the two different elements to the rock separately: releasing the detonation products from the confined bore hole artificially, at the suitable moment when the gas expansion is just going to work, after the moment when the dynamic energy have been given thoroughly to the rock as same amount as usual.
The result of this experiment showed that the action of the gas expansion could be the main part of rock breakage. And we could confirm that in properly balanced explosive shot, the rock was not broken only by the shock wave.
For example, with the conditions of which the burden W equals to 35 cm, the amount of the charged explosive (18% NIG) is 34g, the diameter and the length of the borehole are 30mm and 36cm respectively, the rock was broken completly, and the blasting result was excellent.
And under the same conditions except for W=30cm, and without the work of gas expansion, the rock was not broken, and remained without any effect from the standpoint of practical blasting result.