Classification systems of rock masses have been developed considerably and serve as transmitters of their characteristics. They are also used in the design of engineering solutions, especially in tunnels, which have been developed in the last 60 years. Its use in the determination of engineering solutions covers from the observational method with varying degrees of disaggregation until processing systems of rock mass parameters that are integrated in databases. In both cases, there is a different intensity in the use of theoretical design elements. This has generated two paths that are epistemologically assimilated to the paradigms of the theory and practice of design support systems. Differences and similarities and their importance in the design and engineering practice are discussed.
Rock mass classification systems not only describe them, but they are part of the engineering design methodologies. In its assessment, there are different criteria according how they are used. This leads to some conceptual confusion and employment gaps.
In literature discussions, it can be found two trends that can be visualized in figure 1 [1] [2]. On left it is shown a flowchart of Austrian Standard ON 2203 [3] and on the right are the RMR [4] and Q [5] systems. This type of dissimilar comparisons can be misleading and is discussed in this paper.
In geotechnical engineering there are two modes of thought, resulting in the existence of Paradigms of Theory and Engineering Practice, as described by Vick [6]. The Paradigm of Theory holds to the deductive precept of reasoning from first principles. The Paradigm of Practice is related with empiricism. This is particularly marked in the Rock Mechanics, whose development is relatively recent [7].
