GATE 2021 MN – Question 28

Geomechanics and Ground Control · Ground Control · 1 mark · Multiple choice

Which plotted curve represents coal-pillar vertical stress versus extraction ratio R in a horizontal bord-and-pillar panel?

Curve A
Curve B
Curve C
Curve D

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Show answer and explanation

Correct answer: (C) Curve C

Explanation

Under tributary-area loading, pillar stress scales as overburden stress divided by(1−R). It rises increasingly rapidly as extraction approaches unity, giving the convex upward trend C. The sketch is qualitative; its common drawn origin should not imply zero pillar stress at zero extraction.

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