ROCK MASS CLASSIFICATION - REVIEW | ROCK TUNNELLING
SYSTEMS: A REVIEW CLASSIFICATION ROCK MASS
This paper reviews and discusses the international distribution and development of Rock Mass Classification systems
Authors Georg H. Erharter1,2, Neil Bar3, 2 Tom F. Hansen1, Sumit Jain4, Thomas Marcher2 1 Norwegian Geotechnical Institute, Oslo, Norway
Institute of Rock Mechanics and Tunnelling, Graz University of Technology, Graz, Austria 3
Gecko Geotechnics, Kingstown, Saint Vincent and the Grenadines 4
Rail Vikas Nigam Limited (RVNL), New Delhi, India
ABSTRACT Since the 1950s, numerous rock mass classification systems (RMCS) have emerged for applications such as tunnelling, mining, and slope engineering. The continued proliferation of these systems reflects the complexity of the issue and the absence of a universally accepted approach within the rock engineering community. This review offers an up-to-date examination of the global utilisation of RMCS across applications such as tunnels, caverns, mining slope stability, and more. A ‘family tree of rock mass classification systems’ is
presented that traces their evolution over the decades. The family tree illustrates a prolific period of system development between 1970 and 2000, followed by a decline in progress and increasing specialisation of systems. Based on surveys within the rock engineering community carried out between 2022 and 2024, the dominant systems for underground engineering and slope-related tasks were found to be GSI, RMR, and the Q-system, which have demonstrated their practical efficacy over five decades. Based on the surveys, ‘world maps of rock mass
classification’ have been produced that visualise the international RMCS distribution. However, the survey shows that only some new or derived systems developed in the last 25 years have gained global acceptance. The paper closes with an outlook to possible future developments in rock mass classification and characterisation.
Highlights ● A comprehensive compilation of 37 rock mass
classification systems, created by literature research and international surveys.
● A family tree of rock mass classification systems is presented, showing the main development strands and derived systems.
● Mapping shows the global distribution of rock mass classification systems for underground engineering and slope engineering.
● Discussion of ways to move forward with rock mass classification, considering modern technology and scientific practices.
1 INTRODUCTION Rock mass is comprised of the intact rock material together with discontinuities and weathering zones, and cavities with liquid or gaseous infilling, often with anisotropic properties. Considering this geological material and its complex
properties, rock engineering design and construction are inherently challenging. In response, engineers developed a plethora of
systems throughout the decades to classify rock mass into discrete classes, often based on assessed and computed continuous metrics, which help to communicate rock mass conditions and ease the rock engineering design process. Today, dozens of rock mass classification systems (RMCS) exist which is symptomatic of the underlying challenge of describing this natural material. Besides geological complexity, the plethora of existing RMCS can also be attributed to the development of national systems, adaptations to machine logistics, contract regimes, and local rock engineering practices. Ongoing technical debates among scholars and practitioners (Daller et al. 1994; Riedmüller and Schubert 1999; Anagnostou and Pimentel 2012) show that the community has not yet found an optimum solution to that problem. This contribution aims to provide a global overview of
the current state of rock mass classification as of 2024. It provides the rock engineering community with two main products:
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