Q-system (geotechnical engineering)

For the linguistics formalism, see Q-systems.

The Q-system of rock mass classification was developed in Norway in 1974 by Nick Barton, Lien, R., and Lunde, J at NGI (Norwegian Geotechnical Institute). The system was developed on the basis of an analysis of 212 tunnel case histories from Scandinavia. It is a quantitative classification system and is an engineering system facilitating the design of tunnel supports. The Q-system uses six different parameters to assess the rock mass quality. The parameters are:

• Rock Quality Designation RQD
• Joint set number J_n
• Roughness of the most unfavorable joint or discontinuity J_r
• Degree of alteration of filling along the weakest joint J_a
• Water inflow J_w
• Stress Reduction Factor SRF

The Q-factor can then be calculated as:

$Q={\frac {RQD}{J_{n}}}{\frac {J_{r}}{J_{a}}}{\frac {J_{w}}{SRF}}$

References

• Barton, N.R. (2000). TBM Tunnelling in Jointed and Faulted Rock. Taylor & Francis. p. 184. ISBN 978-9058093417.
• Barton, N. 2002. "Some new Q-value correlations to assist in site characterization and tunnel design", Int. J. Rock Mech. & Min. Sci. Vol. 39/2:185-216.
• Barton, N. 2006. Rock Quality, Seismic Velocity, Attenuation and Anisotropy. Taylor & Francis, UK & Netherlands, 729 p.
• Barton, N. & Grimstad, E. 1994. "The Q-system following twenty years of application in NMT support selection", 43rd Geomechanic Colloquy, Salzburg. Felsbau, 6/94. pp. 428–436.
• Barton, N. Lien, R. & Lunde, J. 1974. "Engineering classification of rock masses for the design of tunnel support", Rock Mechanics. 6:4:189-236.
• Barton, N. Lien, R. & Lunde, J. 1977. "Estimation of support requirements for underground excavations", Proc. of 16th Symp. on Design Methods in Rock Mechanics, Minnesota, 1975. pp. 163–177. ASCE, NY. Discussion pp. 234–241.
• Grimstad, E. & Barton, N. 1993. Updating the Q-system for NMT. Proc. of the International Symposium on Sprayed Concrete - Modern Use of Wet Mix Sprayed Concrete for Underground Support, Fagernes, 1993, (Eds. Kompen, Opsahl and Berg) Norwegian Concrete Association, Oslo.

Further reading

• Bieniawski, Z.T. "Engineering Rock Mass Classifications", John Wiley and Sons, New York, 1989
• Hack, H R G K (1998). Slope stability probability classification SSPC, 2nd edition, ITC publication no 43, Enschede, Netherlands, ISBN 90-6164-154-3 (258).
• Pantelidis, L (2009). "Rock slope stability assessment through rock mass classification systems", International Journal of Rock Mechanics and Mining Sciences, 46(2), (315–325).

See also

• Rock Structure Rating
• Hoek-Brown failure criterion