Research on the Reasonable Width of the Waterproof Coal Pillar during the Mining of a Shallow Coal Seam Located Close to a Reservoir

Table 1

Determination methods of the widths of waterproof coal pillars in different conditions.

Coal seam mining in different cases	Width of waterproof coal pillar	Considered influence factors
Under an aquifer	The height of water-conducting fracture zone + the thickness of the protective layer	(1) Lithology of overlying strata [16, 17]; (2) Dip angle of coal seam [18, 19]; (3) Key stratum [20–23]; (4) Changes of the characteristic parameters of overlying strata [24, 25]; (5) Height of coal seam [20, 26]; (6) Depth of coal seam [3, 27]; (7) Stability of coal pillar [20, 28]; (8) Water pressure and mine pressure [17]
Adjacent to the water-conducting fault	(1) The empirical formula considered the effects of water pressure; (2) A coal-mining-influenced zone + an elastic waterproof zone + a fault-affected zone	(1) Water pressure and mine pressure [29–33]; (2) Dip angle of fault [29–31]
In section	A plastic zone + an elastic core zone + a hydraulic fractured zone	(1) Stability of coal pillar [34, 35]; (2) Water pressure and mine pressure [36]
Close to a reservoir	A mine-pressure-influenced zone + an effective waterproof zone + a water-level-influenced zone	(1) Water level and the distribution of the phreatic line in the bank slope (in this paper); (2) Stability of the bank slope (in this paper)