The shale roof some times gives a ringing sound, if thick ness of shale greater than . . . . . . . .
A. 0.1m
B. 0.2m
C. 0.5m
D. 0.3m
Answer: Option D
Related Questions on Mine Supports and Strata Control
The minimum length of sleeper used as chock support of the roof height to be supported excess of 3m.
A. 1.2 m
B. 1.5 m
C. 1.6 m
D. 1 m
The preferred shape of an opening in uniaxial stress field as
A. Circle
B. Ellipse
C. Ellipse with proper axis ratio
D. Ovaloid
Most of the Gondwana coals from any field are rich in . . . . . . . .
A. Durain
B. Fusain
C. Vitrain
D. Clairain
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