 Rock Quality Designation (RQD)
NGI Rock Tunneling Quality Index (Q) CSIR Rock Mass Rating (RMR) Mining Rock Mass Rating (MRMR) Coal Mine Roof Rating (CMRR) Rock mass classification is a means of evaluating the quality and expected behaviour of rock masses based on the most important parameters that influence the rock mass quality. Numerous researchers have developed rock mass classification systems and each may be more appropriate than others to use in different circumstances. One of the first such systems to be developed is the Rock Quality Designation (RQD) system (Deere, 1988). This system only accounts for the frequency of jointing within a rock mass as a measure of its quality. Later systems which have been developed such as the RMR and NGI Rock Tunneling Quality Index use the RQD as on of their measurable parameters, but also include factors such as intact rock strength, joint spacing, joint condition, field stress, and groundwater effects. Rock mass classification systems are important because they provide a consistent means of describing quantitatively the rock mass quality. This in turn has led to the development of many empirical design systems involving rock masses. Some of these empirical design systems include: - open stope span and support design
- man-entry stope span design
- tunneling support design
- pillar design
- roadheader cuttability assessment
- rock slope design
- underground excavation stand-up time
- suitability for block caving
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