The precision and reliability of the volume characteristics of individual rock fractures

Abstract

1. The volumetric characteristics of single acts of rock breaking by the most widespread present-day techniques of mechanical and blast fragmentation are determined by the total yield of rock from the zones of active fragmentation and of rubble. 2. The relative importance of the caving (rubble) volume in the total fragmentation volume in all the methods examined is as a rule large, and sometimes absolutely predominates, reaching 90% or even more. It is therefore fundamentally erroneous not to allow for the volume of caving (rubble) in the volumetric characteristics of single acts of fragmentation. 3. The dimensions of the caving zone and the relative volume of the latter may be influenced by the characteristics of the fragmentation process; the intensity of this influence will be different in rocks with different properties. It is thus fundamentally incorrect to allow for the volume of rubble by any single constant coefficient. 4. The standard deviations of the volumetric characteristics of single acts of fragmentation of rocks are, as a rule, large, and are not constant but can vary sharply according to the properties of the rock and the characteristics of the fragmentation process. For this reason, the variability of the volumetric characteristics of fragmentation must be allowed for in engineering calculations.