Rock Engineering and Rock Mechanics: Structures in and on Rock Masses, p. 375-380
DOI: 10.1201/b16955-62
Due to the large experience accumulated in the use of the RMRb (Rock Mass Rating), as well as to the simplicity of the estimation of the GSI (Geological Strength Index) and to the importance of GSI as input data in the Hoek&Brown failure criteria, both the RMRb and GSI are widely used in geotechnical engineering practice. This article analyzes the relationship between both classifications using in situ data corresponding to different types of rocks collected from different outcrops in Spain. Currently available correlations between RMRb and GSI have been compiled and analyzed in order to compare them with the results of the analysis conducted in this study. Finally, the best (most suitable) statistical relations between RMRb and GSI, depending on the type and quality of rock media, are shown and they are used to establish general correlations. To conclude recommendations are presented, suggesting the use of a particular expression and its limits of applicability.