Mining Engineering > GATE 2024 > Underground Coal Mining
A Bord and Pillar panel is developed at a depth of 250 m in a flat coal seam. The vertical stress gradient is 0.027 MPa/m. If the strength of a square pillar is 12.5 MPa, the extraction ratio of the pillar for a safety factor of 1.5, is ________.(round off up to 2 decimals)
Correct : 0.53
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