Q-system

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. Q-system use 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:

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