An improved definition of rock quality designation

Rock Engineering 2009 - Rock Engineering in Difficult Conditions
Li Li, Michel Aubertin,
Abstract The rock quality designation, RQD, is a fundamental index for the description of rock and rock mass quality. Even though the concept was introduced mainly for civil engineering by Deere (Deere 1963; Deere et al. 1967), its application has been largely used and extended for mining engineering projects (e.g., Hoek and Brown 1980; Brady and Brown, 1992; Hoek et al. 1995). The success of the RQD in engineering is due, in great part, to its simplicity. There are however a number of limitations to the application of the RQD, including among other factors a dependency on borehole orientation and the arbitrary selected threshold value for the minimum intact core length (e.g., Harrison 1999; Hack 2002).

In this paper, these limitations will be reviewed and discussed. A new approach will be proposed to overcome, at least in part, the limitations of the original definition of the RQD. This leads to a new (improved) definition of rock mass quality designation.
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