Process / pipelineRock Mass Classification
Q-System
The Q-System (NGI Index), introduced by Nick Barton and colleagues at the Norwegian Geotechnical Institute in 1974, is an alternative rock mass classification to RMR. It combines six parameters into a dimensionless index Q ranging from 0.001 to 1000, where higher Q values indicate better rock quality. The Q-System is particularly valued for tunnel and underground excavation design due to its explicit consideration of joint roughness and groundwater effects.
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Sources
- Barton, N., Lien, R., & Lunde, J. (1974). Engineering classification of rock masses for the design of tunnel support. Rock Mechanics, 6(4), 189-236. DOI: 10.1007/BF01239496 ↗
- Barton, N. (2002). Some new Q-value correlations to assist in site characterisation and tunnel design. International Journal of Rock Mechanics and Mining Sciences, 39(2), 185-216. DOI: 10.1016/S1365-1609(02)00011-4 ↗