Geotechnical studies and investigations are a complement to geology and hydrogeology. Their objectives are to know the basic characteritics of rock masses, the initial state of equilibrium of the natural stresses and the changes during the construction. 
Many Classification Systems have been proposed; three remain in popular use:
– Rock Quality Designation (RQD) by Deere (Now used as input to RMR and Q)
– Rock Mass Rating (RMR) by Bieniawski
– Rock Tunnelling Quality Index (Q) by Barton
Parameter | Max Points | Uniaxial compressive strength of intact rock | 15 | Rock Quality Designation (RQD) | 20 | Spacing of discontinuities | 20 | Condition of discontinuities | 30 | Groundwater conditions | 25 | Adjustment for unfavorable orientation of joints | Reduce RMR by
2 to 12 Points |
Barton’s Q System
Q = (RQD/Jn) x (Jr/Ja) x (Jw/SRF) Rock Mass Condition | Q System Parameter | RQD | RQD | Number of joint sets | Jn | Joint roughness | Jr | Joint alteration | Ja | Joint water | Jw | Stress reduction factor | SRF |
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