Prediction of the blastability designation of rock masses using fuzzy sets

Abstract

The main objective of rock blasting design is to achieve a balance among optimum powder factor, proper fragmentation, throws, ground vibration, etc. The in-situ rock mass properties are among the most important contributory factors in fragmentation. The term blastability is used to indicate the susceptibility of the rock mass to blasting and its characterization has become a pressing task for blasting operations. Several approaches have been used for estimating blastability. Despite their widespread use in practice, they have some common deficiencies leading to uncertainties in their practical applications through sharp transitions between two adjacent rating classes and the subjective uncertainties on data, which are close to the range boundaries of rock classes. In this study, the fuzzy set theory was applied to blastability designation (BD) classification systems. Furthermore, a new methodology in terms of "Effective Rules" is developed in construction of rule base part of the Mamdani fuzzy inference system structure, to efficiently solve fuzzy inference systems with a large number of fuzzy rules (e.g. nearly 400,000 rules). In comparison with the conventional methods, it was seen that the fuzzy model operated more consistently. Moreover, it was shown that the fuzzy set theory could effectively overcome the uncertainties encountered in the practical applications of conventional classification systems.