Abstract
The RMR rock massif rating classification and the Q quality index are the two most common classification systems used in the preliminary design of underground workings. Geotechnical core documentation is usually organized around one of these systems in mining practice, whereas design tools, diagrams of supports, and numerical modeling may require another. The article presents a method for converting a database of geotechnical core descriptions based on the RMR system into Q-ratings using the example of the gold deposit X. The database includes 991 documented intervals for nine geotechnical wells, of which 425 intervals yielded complete and reliable pairs of values of the basic RMR and the modified quality index Q’ . Several regression models have been tested. The proposed equations are compared with known published correlations and showed the smallest prediction errors for the studied massif. Equations for individual lithological groups have also been obtained, confirming that the correlation is closer for sedimentary rocks than for intrusive ones. The results are a practical tool for the initial assessment of Q-ratings based on existing RMR databases at the stage of preliminary design of underground mining workings and are applicable in the studied range of RMR = 31–78.