ROCK TUNNELLING | ROCK MASS CLASSIFICATION - REVIEW
Above, figure 3: Bar charts for each investigated application indicate in how many countries each of the given systems was ranked number 1. A “tie” indicates that two or more systems reached the same number of suggestions in a country
impression of the rock mass conditions in combination
with direct measures, such as drilling or surface scanning. This technology can, therefore, contribute to a closer approximation of the real rock mass conditions and can also contribute to being better aware of existing uncertainties. Although some RMCS have general correlations
with and can be supplemented by data from modern technology, they still require validation with physical access to drill core or rock faces for certain elements (Barton 2002; Bar et al. 2021). No RMCS has yet been developed specifically to integrate with modern technology and digital data.
6 CONCLUSION AND OUTLOOK A survey about the worldwide use of RMCS shows a considerable diversity of systems in use, while only a few (GSI, RMR, Q-system) are majorly used today. Furthermore, the historical development of RMCS is reconstructed and presented in the form of a family tree that shows that some RMCS served as parents for many new developments (e.g., RMR) but also that there were some parallel developments throughout the decades that only recently started to approach one another (e.g., A-BQ). While this paper is not the first review of RMCS, it
is the first to visually show the diversity in the form of maps and a family tree; it enriches the existing body of knowledge with these graphical components. It is this systematic mapping and historical reconstruction that led to the insight presented in the discussion chapter
22 | June 2025
about the newly developed RMCS, showing minor differences and incremental improvements with respect to the systems developed in the 1950s to 1970s. While there are several barriers such as different
geological- or site-specific conditions, cultural differences, and available technical equipment that make progress challenging, there are several ways to go forward. One way is to further develop existing systems to make them more use-case specific. While this might contribute to the further proliferation of RMCS and make future maps even more colourful, it is questionable if this will ever lead to a groundbreaking improvement in rock engineering. As elaborated in the previous section, incrementally adapting existing RMCS without significant conceptual or technological changes does not seem to answer old challenges. Consequently, another way is to develop new
RMCS that are either generally better or better for specific use-cases than existing ones. A challenge in this endeavour is, however, that the new development
of RMCS is inherently dependent on further developments in rock engineering design practices that utilise the output of rock mass classification and characterisation. A newly developed RMCS is futile if there is no
geotechnical design or analysis method that utilises it. Conducting full-scale geotechnical field tests to obtain in-situ mechanical rock mass parameters and probabilistic back analyses from on-site deformation monitoring is seen to play a vital role in developments like that. Furthermore, technical deficits of RMCS need
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