Rock mass classification
Encyclopedia
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 the 1940s for tunnel
s with steel set support.
Geotechnical engineering
Geotechnical engineering is the branch of civil engineering concerned with the engineering behavior of earth materials. Geotechnical engineering is important in civil engineering, but is also used by military, mining, petroleum, or any other engineering concerned with construction on or in the ground...
was proposed in the 1940s for tunnel
Tunnel
A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...
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 to:- 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:- Improving the quality of site investigations by calling for the minimum input data as classification parameters.
- Providing quantitative information for design purposes.
- Enabling better engineering judgement and more effective communication on a project.
Recent systems
- Mining rock mass ratingMining rock mass ratingLaubscher developed the Mining Rock Mass Rating system by modifying the Rock Mass Rating system of Bieniawski. In the MRMR system the stability and support are determined with the following equations:...
(MRMR) - New Austrian Tunnelling MethodNew Austrian Tunnelling methodThe New Austrian Tunnelling method was developed between 1957 and 1965 in Austria. It was given its name in Salzburg in 1962 to distinguish it from old Austrian tunnelling approach. The main contributors to the development of NATM were Ladislaus von Rabcewicz, Leopold Müller and Franz Pacher...
(NATM) (an underground excavation methodology that mostly includes a qualitative ground classification) - Rock Mass RatingRock mass ratingThe rock mass rating system is a geomechanical classification system for rocks, developed by Z. T. Bieniawski between 1972 and 1973.-Definition:The following six parameters are used to classify a rock mass using the RMR system...
(RMR)Rock mass ratingThe rock mass rating system is a geomechanical classification system for rocks, developed by Z. T. Bieniawski between 1972 and 1973.-Definition:The following six parameters are used to classify a rock mass using the RMR system... - Q-systemQ-system (geotechnical engineering)The Q-system for rock mass classification is developed by Barton, Lien, and Lunde. It expresses the quality of the rock mass in the so-called Q-value, on which are based design and support recommendations for underground excavations....
- Size Strength classificationSize Strength classificationSize strength classification is a two-parameter rock classification based on the strength of intact rock and the spacing of discontinuities in the rock mass...
Systems for slope engineering
- An alternative rock mass classification system for rock slopes (DOI: 10.1007/s10064-009-0241-y) http://www.springerlink.com/content/m14t4057126h5015/?p=4f936f8fa70f48828eeba60d58d676d9&pi=8
- Slope Stability Probability ClassificationSlope stability probability classificationThe slope stability probability classification system is a rock mass classification system for slope engineering and slope stability assessment...
(SSPC)http://www.xs4all.nl/~hack/WORKHack/Publications/2003%20sspc/SSPC%20ver%20web.pdf - Slope Mass Rating (SMR)
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 TerzaghiKarl von TerzaghiKarl von Terzaghi was an Austrian civil engineer and geologist, called the father of soil mechanics.-Early life:...
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 shotcreteShotcreteShotcrete is concrete conveyed through a hose and pneumatically projected at high velocity onto a surface, as a construction technique....
and rock bolts. - 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 New Austrian Tunnelling MethodNew Austrian Tunnelling methodThe New Austrian Tunnelling method was developed between 1957 and 1965 in Austria. It was given its name in Salzburg in 1962 to distinguish it from old Austrian tunnelling approach. The main contributors to the development of NATM were Ladislaus von Rabcewicz, Leopold Müller and Franz Pacher...
(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 New Austrian Tunnelling MethodNew Austrian Tunnelling methodThe New Austrian Tunnelling method was developed between 1957 and 1965 in Austria. It was given its name in Salzburg in 1962 to distinguish it from old Austrian tunnelling approach. The main contributors to the development of NATM were Ladislaus von Rabcewicz, Leopold Müller and Franz Pacher...
. - Reference:
- Rock Quality Designation (RQD)
- The Rock Quality Designation system is developed by Deere in the 1960s to classify the quality of a rock mass 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 mass 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 RatingRock Structure RatingRock Structure Rating 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 ....
(RSRRSRRSR, a three letter acronym that may mean:*Radio Suisse Romande the Swiss French public service radio group*Relative survival rate*Resource status report*Reverie Sound Revue, a Canadian band*Former international license plate code for Southern Rhodesia...
)
- The Rock Structure RatingRock Structure RatingRock Structure Rating 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 ....
(RSRRSRRSR, a three letter acronym that may mean:*Radio Suisse Romande the Swiss French public service radio group*Relative survival rate*Resource status report*Reverie Sound Revue, a Canadian band*Former international license plate code for Southern Rhodesia...
) 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.
See also
- Rock mechanicsRock mechanicsRock mechanics is the theoretical and applied science of the mechanical behaviour of rock and rock masses;also compared to the geology, it is that branch of mechanics concerned with the response of rock and rock masses to the force fields of their physical environment.Rock mechanics itself forms...
- Geotechnical investigationGeotechnical investigationGeotechnical investigations are performed by geotechnical engineers or engineering geologists to obtain information on the physical properties of soil and rock around a site to design earthworks and foundations for proposed structures and for repair of distress to earthworks and structures caused...
- Geotechnical engineeringGeotechnical engineeringGeotechnical engineering is the branch of civil engineering concerned with the engineering behavior of earth materials. Geotechnical engineering is important in civil engineering, but is also used by military, mining, petroleum, or any other engineering concerned with construction on or in the ground...
- ISRM classificationISRM classificationThe International Society for Rock Mechanics - ISRM was founded in Salzburg in 1962 as a result of the enlargement of the "Salzburger Kreis". Its foundation is mainly owed to Prof. Leopold Müller who acted as President of the Society till September 1966. The ISRM is a non-profit scientific...
----