Depillaring: Arrangement, Precautions and Pillar
In a method of depillaring, known as the caving method, the coal of the pillars is extracted and the roof is allowed to break and collapse into the voids or the decoaled area, known as goaf. As the roof strata about the coal seam break, the ground surface develops cracks and subsides, the extent of damage depending upon depth, thickness of the seam extracted, the nature of strata, thickness of