The Slope Mass Rating (SMR; Romana, 1985) geomechanics classification was developed as a sequel of Bieniawski's Rock Mass Rating (RMR) system, which was almost impossible to use in slopes due to the extreme range of the correction factors (up to 60 points of a maximum of 100) and to the lack of definition of them. A detailed quantitative definition of the correction factors is one of the advantages of SMR classification. During the last thirty years the use of SMR system has been extended to many countries from the five continents and, thus, it is time to review the most interesting developments. Both RMR and SMR are discrete classifications, depending on the values adopted by the variables that control the parameters. This can cause major changes in the parameters value due to small differences in the variables value, with changes in the final rock mass assigned quality. On the other hand, geomechanics quality indexes are extremely biased. To avoid this problem, some authors have proposed continuous functions for SMR. This classification has been also adapted for its application in heterogeneous and anisotropic rock masses, for high slopes, for is application trough stereographic projection and Geographical Information Systems, has been used as susceptibility rockfall parameters and has been included in the technical regulations of several countries. Additionally, some open access computer tools have been developed for the computation of SMR. Consequently, this paper reviews:
the most important modifications and adaptations of slope classifications which derive directly from SMR;
the use of SMR throughout the world;
many significant papers on slopes analysed with SMR all over the world; and
future trends in the use of SMR.
Rock mass classifications are a universal communication system for engineers which provide quantitative data and guidelines for engineering purposes that can improve originally abstract descriptions of rock mass from inherent and structural parameters (Pantelidis, 2009) by simple arithmetic algorithms. The main advantage of rock mass classifications is that they are a simple and effective way of representing rock mass quality and of encapsulating precedent practice (Harrison and Hudson, 2000). Some of the existing geomechanical classifications for slopes are Rock Mass Rating (RMR, Bieniawski, 1976; 1989), Rock Mass Strength (RMS, Selby, 1980), Slope Mass Rating (SMR, Romana, 1985), Slope Rock Mass Rating (SRMR, Robertson, 1988), Chinese Slope Mass Rating (CSMR, Chen, 1995), Natural Slope Methodology (NSM, Shuk, 1994), Slope Stability Probability Classification (SSPC, Hack et al., 2003), modified Slope Stability Probability Classification (SSPC modified, Lindsay et al., 2001), Continuous Rock Mass Rating (Sen and Sadagah; 2003), Continuous Slope Mass Rating (Tomás et al., 2007), Fuzzy Slope Mass Rating (FSMR; Daftaribesheli et al., 2011) and Graphical Slope Mass Rating (GSMR; Tomás et al., 2012). Some of the above mentioned geomechaniccs classifications are variants from the original ones. SMR is universally used (Romana et al., 2003). SMR is computed from basic RMR (Bieniawski, 1989) which was originally proposed for tunnelling but also included a correction factor for slopes to take into account the influence of discontinuities orientation on the slope stability which was almost impossible to be used due to the extreme range of the correction factors (up to 60 points of a maximum of 100) and to the lack of definition of them in practice. In this paper a review of the last thirty years of the SMR is performed, discussing its main modifications, adaptations and applications worldwide.