ABSTRACT
The determination of the parameters by direct or laboratory methods is very costly and difficult, as the samples tested do not usually include discontinuities and the lithological changes of the rock mass from where they were taken. In order to obtain a representative sample, it would be necessary for it to have a size ten times larger than the mean spacing between joints. There are various properties of the joints that can be measured in a characterization study, but the most important from a breakage point of view are spacing and orientation. A. K. Ghose also proposes a geomechanic classification system of the rock masses in coal mines for predicting powder factors in surface blastings. An attempt to take into consideration the structural discontinuities when designing the rounds is owed to J. P. Ashby, which relates the fracture frequency and their shear strength to the powder factors of the explosive.
