Appendix C: Rock mass
classification tables
- RMR and Q
The following tables are provided to support the questions in Chapter 12.
Note that although we have used the term 'fracture' in this book, the
originators of the RMR and Q classifications used the words 'discon-
tinuity' and 'joint', respectively. To avoid confusion with the original
publications we have retained these words in the tables below.
Rock mass rating system1
RMX = C(c1assification parameters)
+ discontinuity orientation adjustment(A) Classification parameters and ratingsStrength of intact rock material
Point-load strength * 1-2 24 4-10 >10
index (MPa)
Uniaxialcompressive tl 1-5 5-25 2550 50-100 100-250 ,250
strength (MPa)
Rating: 01 2 4 7 12 15
* For this low range, uniaxial compressive test is preferred.
Groundwater
Inflow per 10-m tunnel ,125 25425 10-25 110 none
length (l/min)
Ratio >0.5 0.2-0.5 0.1-0.2 tO.l
General conditions flowing dripping wet damp completely dry0
joint water pressure
major principal stressRating: 0 4 7 10 15' Bieniawslu Z. T. (1989) Engineering Rock Muss Classifications. Wiley, Chichester, 251pp.