Encyclopedia of Engineering Geology

2018 Edition
| Editors: Peter T. Bobrowsky, Brian Marker

Rock Mass Classification

  • William H. GodwinEmail author
Reference work entry
DOI: https://doi.org/10.1007/978-3-319-73568-9_244


Ground classification; Rock strength classification


A classification system that captures all relevant information on the composition and characteristics of a rock mass to provide initial estimates of support requirements and to provide estimates of the strength and deformation properties of the rock mass.


One of the earliest classification systems for rock was developed by Terzaghi (1946). The classification system was developed as a method of classifying rock masses and evaluating rock loads based on qualitative assessments.

The rock-quality designation (RQD) developed by Dr. Don U. Deere (Deere and Deere 1988) is a method of logging sound drilled rock core to calculate and quantify the percentage of “good” rock in a core run. RQD is a quantitative method of evaluating rock quality and is widely used as one of the parameters in other more numerical rock classification systems.
$$ \mathrm{RQD}=\mathrm{Sum}\ \mathrm{of}\ \mathrm{length}\...
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© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.CarmelUSA