Engineering Geological Assessment of Diversion Tunnel of Bakhtiari Damsite (Biggest Two-Arch Concrete Dam in Southern Iran)

Table 8

Ranges of 𝑄 values and description of the rock-mass classes.

𝑄	Rock-mass class	Description
1000–400	I	Exceptionally good
400–100		Extremely good
100–40		Very good
40–10		Good
10–4	II	Fair
4–1		Poor
1–0.1		Very poor
0.1–0.01	III	Extremely poor
0.01–0.001		Exceptionally poor