Determination of Water-Proof Coal (Rock) Pillar Height in Mining Coal Seam Group under Water-Bearing Rock Stratum

Figure 3

The coal seam outcrops were left pictures of water-proof coal (rock) pillar covered with loose, water-rich, and powerful water-bearing rock formations. (1) Water-conducting fracture zone. (2) Water-proof protective rock stratum. (3) Seam floor.