炭たん柱ちゅう

noun

coal pillar

Technical term used in mining to refer to a pillar of coal left in place to support the roof of a mine.

• 炭たん柱ちゅうを残のこして採さい掘くつする方ほう法ほうは、坑こう道どうの安あん定ていに役やく立だつ。

  The method of mining while leaving coal pillars helps stabilize the tunnels.