Rock mass classification systems are used for various engineering design and stability analysis. These are based on empirical relations between rock mass parameters and engineering applications, such as tunnels, slopes, foundations, and excavatability. The first rock mass classification system in geotechnical engineering was proposed in 1946 for

tunnel A tunnel is an underground passageway, dug through surrounding soil, earth or rock, and enclosed except for the entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube cons ...

s with steel set support.

Design methods

In engineering in rock, three design strategies can be distinguished: analytical, empirical, and numerical. Empirical, i.e. rock mass classification, methods are extensively used for feasibility and pre-design studies, and often also for the final design.

Objectives

The objectives of rock mass classifications are (after Bieniawski 1989): # Identify the most significant parameters influencing the behaviour of a rock mass. # Divide a particular rock mass formulation into groups of similar behaviour – rock mass classes of varying quality. # Provide a basis of understanding the characteristics of each rock mass class # Relate the experience of rock conditions at one site to the conditions and experience encountered at others # Derive quantitative data and guidelines for engineering design # Provide common basis for communication between engineers and geologists

Benefits

The main benefits of rock mass classifications: # Improve the quality of site investigations by calling for the minimum input data as classification parameters. # Provide quantitative information for design purposes. # Enable better engineering judgement and more effective communication on a project. # Provide a basis for understanding the characteristics of each rock mass

Rock mass classification systems

Systems for tunneling: Quantitative

Rock Mass Rating The rock mass rating (RMR) is a geomechanical classification system for rocks, developed by Z. T. Bieniawski between 1972 and 1973. Since then it has undergone multiple modifications out of which, RMR89 is commonly used. Recently RMR14 has been ...

(RMR) * Q-system * Mining rock mass rating (MRMR)

Other systems: Qualitative

New Austrian Tunnelling Method The New Austrian tunneling method (NATM), also known as the sequential excavation method (SEM) or sprayed concrete lining method (SCL), is a method of modern tunnel design and construction employing sophisticated monitoring to optimize various wa ...

(NATM) * Size Strength classification

Systems for slope engineering

* Slope Mass Rating (SMR), Continuous Slope Mass Rating and Graphical Slope Mass Rating * Rock mass classification system for rock slopes * Slope Stability Probability Classification (SSPC)

Earlier systems

*Rock load classification method :The ''Rock load classification method'' is one of the first methodologies for rock mass classification for engineering.

Karl von Terzaghi Karl von Terzaghi (October 2, 1883 – October 25, 1963) was an Austrian mechanical engineer, geotechnical engineer, and geologist known as the "father of soil mechanics and geotechnical engineering". Early life In 1883, he was born the first ch ...

developed the methodology for tunnels supported by steel sets in the 1940s. By many regarded as obsolete as ideas about rock and rock mass mechanical behavior have since further developed and the methodology is not suitable for modern tunneling methods using

shotcrete Shotcrete, gunite (), or sprayed concrete is concrete or mortar conveyed through a hose and pneumatically projected at high velocity onto a surface, as a construction technique, first used in 1907 invented by Carl Akeley. It is typically ...

and

rock bolt A rock bolt is a long anchor bolt, for stabilizing rock excavations, which may be used in tunnels or rock cuts. It transfers load from the unstable exterior to the confined (and much stronger) interior of the rock mass. Rock bolts were first use ...

s. :Reference: also in ''Soil Mechanics Series 25'', publication 418. Harvard University, Graduate School of Engineering. *Stand-up time classification :The ''Stand-up time classification'' by Lauffer is often regarded as the origin of the ''

'' ''(NATM)''. The original system as developed by Lauffer is nowadays by many regarded as obsolete but his ideas are incorporated in modern rock mechanics science, such as the relation between the span of a tunnel and the stand-up time, and notably in the

. :Reference: *

Rock Quality Designation Core recovery parameters describe the quality of core recovered from a borehole. Total core recovery Total core recovery (TCR) is the borehole core recovery percentage. TCR is defined as the quotient: :TCR = \left(\frac\right)\times 100 % :l_\ma ...

:The ''

'' index was developed by Deere in the 1960s to classify the quality of a rock core based on the integrety of borehole cores. Nowadays the classification system itself is not very often used, but the determination of the RQD as index for rock core quality is standard practice in any geotechnical rock drilling, and is used in many, more recent, rock mass classification systems, such as ''RMR'' and ''Q-system'' (see above). *

Rock Structure Rating Rock Structure Rating (RSR) is a quantitative method for describing quality of a rock mass and appropriate ground support, in particular, for steel-rib support, developed by Wickham, Tiedemann and Skinner. The RSR concept introduced a rating syste ...

(RSR) :The

system is a quantitative method for describing quality of a rock mass and appropriate ground support, in particular, for steel-rib support, developed by Wickham, Tiedemann and Skinner in the 1970s.