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Q-system (geotechnical engineering)

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For the linguistics formalism, see Q-systems.

The Q-system for rock mass classification was developed by Barton, Lien, and Lunde[1][2][3][4][5][6][7][8] and updated by Grimstad and Barton[9][10][11] particularly concerning the use of fibre-reinforced shotcrete. 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 covering a wide range of dimensions, i.e. tunnels from about 3m span to caverns of about 60m span (as per Gjøvik Olympic Cavern Hall).

The Q-value is determined with

The first term RQD (Rock Quality Designation) divided by Jn (joint set number) is related to the size of the intact rock blocks in the rock mass. The second term Jr (joint roughness number) divided by Ja (joint alteration number) is related to the shear strength along the discontinuity[disambiguation needed] planes and the third term Jw (joint water parameter) divided by SRF (stress reduction factor) is related to the stress environment on the intact rock blocks and discontinuities around the underground excavation.

A multiplication of the three terms results in the Q parameter, which typically ranges from 0.001 for exceptionally poor rock mass to 1000 for exceptionally good rock mass. The numerical values for class boundaries indicating different rock mass qualities are subdivisions of the Q range on a logarithmic scale. For instance Q = 1 to 4 is 'poor' quality, Q = 4 to 10 is 'fair' quality and Q = 10 to 40 is 'good' quality. Significantly less tunnel or cavern support is needed over this central range of Q.

The Q system is widely used in both civil and mining engineering, for characterising drill-core and rock and tunnel exposures, and for assisting with tunnel and cavern support selection, using single-shell shotcrete and rock bolt support, usually without final concrete linings.

In mining, the first four parameters of Q are used in stope characterisation, differentiating stable from caving ground[12], and giving the possibility of predicting the dilution of the ore with unwanted over-break of the walls of the stopes.

Q has also been linked to seismic velocity and to deformation modulus. Both of these rock mass parameters are depth or stress-dependent.[6][7][10][11]

An extended version of Q, including some rock-cutter interaction parameters, is used for TBM prognosis.[5]


References

  1. ^ Barton, N.R.; Lien, R.; Lunde, J. (1974). "Engineering classification of rock masses for the design of tunnel support". Rock Mechanics and Rock Engineering. 6 (4). Springer: 189–236. doi:10.1007/BF01239496.
  2. ^ Barton, N.R. (1976), Bieniawski, Z.T. (ed.), Recent experiences with the Q-system of tunnel support design, vol. 1, Balkema, Cape Town, pp. 107–117, ISBN 0-86961-089-9 {{citation}}: Unknown parameter |booktitle= ignored (help)
  3. ^ Barton, N.R.; Lien, R.; Lunde, J. (1977), Fairhurst, C.; Crouch, S.L. (eds.), Estimation of support requirements for underground excavations & discussion, American Society of Civil Engineers (ASCE), New York, pp. 163–177, 234–241, OL 19853458M {{citation}}: Unknown parameter |booktitle= ignored (help)
  4. ^ Barton, N.R.; Grimstad, E. (1994). "The Q-system following twenty years of application in NMT support selection; 43rd Geomechanic Colloquy, Salzburg". Felsbau. Verlag Glückauf GmbH, Essen, Germany: 428–436. ISSN 1866-0134.
  5. ^ a b Barton, N.R. (2000). TBM Tunnelling in Jointed and Faulted Rock. Taylor & Francis. p. 184. ISBN 978-90-5809-341-7.
  6. ^ a b Barton, N.R. (2002). "Some new Q-value correlations to assist in site characterization and tunnel design". International Journal of Rock Mechanics and Mining Sciences. 39 (2): 185–216. doi:10.1016/S1365-1609(02)00011-4.
  7. ^ a b Barton, N.R. (2006). Rock Quality, Seismic Velocity, Attenuation and Anisotropy. Taylor & Francis. p. 729. ISBN 978-0-415-39441-3.
  8. ^ Barton, N.R. (1988), Kirkaldie, L. (ed.), Rock Mass Classification and Tunnel Reinforcement Selection using the Q-system, vol. 1, ASTM International, pp. 59–88, doi:10.1520/STP48464S, ISBN 978-0-8031-0988-9 {{citation}}: Unknown parameter |booktitle= ignored (help)
  9. ^ Grimstad, E.; Barton, N.R. (1993), Kompen, C.; Opsahl, S.L.; Berg, S.L. (eds.), Updating the Q-system for NMT, Norwegian Concrete Association, Oslo, pp. 163–177, 234–241, OL 19853458M {{citation}}: Unknown parameter |booktitle= ignored (help)
  10. ^ a b Barton, N.R.; Grimstad, E. (2014a), p. 43 {{citation}}: Missing or empty |title= (help); Unknown parameter |booktitle= ignored (help)
  11. ^ a b Cite error: The named reference BartonGrimstadt2014b was invoked but never defined (see the help page).
  12. ^ Barton, N. (2014), Keynote Lecture: Lessons learned using empirical methods applied in mining [Available for download at www.nickbarton.com], Lima, Peru {{citation}}: Unknown parameter |conference= ignored (help)CS1 maint: location missing publisher (link)

Cite error: A list-defined reference named "BartonGrimstad2014b" is not used in the content (see the help page).

Further reading

  • Bieniawski, Z.T. Engineering Rock Mass Classifications, John Wiley and Sons, New York, 1989
  • Hack, H.R.G.K. (25–28 November 2002). "An evaluation of slope stability classification. Keynote Lecture.". In Dinis da Gama, C.; Ribeira e Sousa, L. (eds.). Proc. ISRM EUROCK’2002. Funchal, Madeira, Portugal: Sociedade Portuguesa de Geotecnia, Lisboa, Portugal. pp. 3–32. ISBN 972-98781-2-9. {{cite conference}}: Unknown parameter |booktitle= ignored (|book-title= suggested) (help)
  • Pantelidis, L (2009). "Rock slope stability assessment through rock mass classification systems", International Journal of Rock Mechanics and Mining Sciences, 46(2), (315–325).
  • Palmstrom, A.; Broch, E. (2006). ""Use and misuse of rock mass classification systems with particular reference to the Q-system"". Tunnelling and Underground Space Technology. 21 (6): 575–593. doi:10.1016/j.tust.2005.10.005.
  • Müller, L. (1966), The progressive failure in jointed media, vol. 3., pp. 679–686 {{citation}}: Unknown parameter |booktitle= ignored (help)
  • Potvin, Y. (1988), Empirical open stope design in Canada, Ph.D. thesis, University of British Columbia, Canada
  • Potvin, Y. and Hadjigeorgiou, J. (2001) "The stability graph method for open-stope design in Underground mining methods: engineering fundamentals and international case studies, Hustrulid & Bullock (Eds). Littleton, CO: Society for Mining Metallurgy and Exploration: 2001 Chapter 60, pages 531-519.


See also

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