RMR vs Q vs RMI

Applicability of the empirical methods on rock mass classification and support estimation has been a subject of discussion since these methods were developed. In order to discuss and compare applicability and reliability of the RMR method, the Q-system and the RMi method, a comparative study has been carried out at NTNU. In this study, 5 observers have done their individual mapping of 3 locations along a proposed tunnel alignment near Trondheim, and convenience in the evaluation of parameters and variation in respective rating values have been assessed. Attempts have been made to identify the reasons for the variation and reproducibility of the rating values. Effect of the rating value variation on the sensitivity of overall classification value has been assessed for each method. The three methods have also been compared in terms of the amount and type of the tunnel support estimation. Despite some significant variations in rating value estimation, the final results concerning rock mass classification and support requirement have been found to be quite similar.