Q391
The average vertical stress in a coal pillar of a B & P panel is found to be 8 MPa. The depth of the pillar and the average density of overburden rock are 200 m and 2500 kg/m3 respectively. Assuming pillar stress to be the same in all coal pillars of that panel, the extraction ratio of the panel is
A.
0.387
AnswerB.
0.513
C.
0.613
D.
0.751
Answer: Option A
Solution
Answer: Option A
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