On the issue of rock resistance during blast-holes spurring

Abstract

The study should give for each rock or its characteristic difference a constant, precisely defined figure, expressing its relationship to spurring of holes adopted in this case. The most desirable would be to obtain figures that, depending entirely on the petrographic nature of the rocks being studied, would, on the other hand, be completely independent of such factors as the force of the drill impact, the diameter of the drill, the angle of its sharpening, the angle of rotation of the drill, etc. In the case when it is impossible to exclude the influence of all these factors, the study must give figures that depend only on some of them, and in this latter case, all the studied rocks must be compared in exactly the same conditions. Figures of the first kind could then be called absolute, and of the second - only relative.