Rock mass characterization for underground hard rock mines, Tunnelling Underground Space Technol

ABSTRACT: Rock mass characterization is an integral part of rock engineering practice. There are several classification systems used in underground mine design, however, most Canadian mines rely on only one of three classification systems. It is interesting to note that these systems, RQD, RMR and Q system, have their origin in civil engineering. This paper reviews the current state of these classification systems as employed in the mining industry. The first part focuses on the determination of the field parameters, with emphasis on the modifications to each parameter over the last 20 years. The difference between classification parameter which influence rock mass strength estimation and those that influence engineering design is emphasized. The second part of the paper focuses on the design recommendations based on these systems such as maximum span, opening geometry and support recommendations. The paper concludes with reference to errors that may arise in particular conditions.