For a granitic rock mass, joint set number (Jn) = 9, joint water reduction factor (Jw) = 1

Q. For a granitic rock mass, joint set number (Jn) = 9, joint water reduction factor (Jw) = 1, joint alteration number (Ja) = 1, stress reduction factor (SRF) = 1, rock quality designation (%) = 84 and joint roughness number (Jr) = 3. The Q-value as per Barton’s Q-system of rock mass classification (year 1974) is 

Ans: 28-28

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