Cocompetitive Characteristics and Quantitative Design of Engineering Parameters for Coal Gas Predrainage Boreholes

Table 3

Parameters of the extracting seam drilling construction layout.

Location		Hole depth	Dip angle	Position	Aperture	Number of boreholes	Total footage	Opening height	Spacing
Track roadway	Air-return measure roadway 38 meters inward	220 m	1~2°	90°	113 mm	118	25960 m	1.5 m	5 m
	Inward from the second setup room	150 m	1~2°	90°	113 mm	307	46050 m	1.5 m	3 m
Belt roadway	Air-return measure roadway 765 meters inward	90 m	-1~-2°	90°	113 mm	307	27630 m	1.5 m	3 m