Mining Engineering > GATE 2023 > Tunneling
A tunnel of diameter 8 m is to be driven in a rock mass having quality index, Q of 1.0. Assume the excavation support ratio (ESR) of the tunnel is 1.0. The support requirement of the tunnel wall using fibre reinforced shotcrete (based on the chart prepared by Grimstad and Barton, 1993) is
A
Shotcrete of thickness 9-12 cm, bolt length of 2.7-2.8 m
B
Shotcrete of thickness 9-12 cm, bolt length of 3.0-3.2 m
C
Shotcrete of thickness 5-9 cm, bolt length of 2.7-2.8 m
D
Shotcrete of thickness 5-9 cm, bolt length of 2.5-2.6 m

Correct : a

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