ABSTRACT
Abdullatif and Cruden (1983) produced a graph of Q against RMR for digging, ripping and blasting, based on investigations at 23 sites. The graph showed that the rock mass can be dug up to an RMR value (see Bieniawski, 1989) of 30 and ripped up to an RMR value of 60. Rock masses rated as 'good' or better by RMR must be blasted.
