Study on the Mechanism and Control of Rock Burst of Coal Pillar under Complex Conditions

Table 4

Parameters of roof precracking blasthole drilling and filling explosive.

Hole number	Borehole length (m)	Horizontal angle (°)	Elevation angle (°)	Borehole diameter (mm)	Filling explosive length (m)	Plugging length (m)	Explosive filling weight (kg)
1	39	90	42	94	26	13	130
2	49	90	25	94	33	16	165
3	45	90	12	94	30	15	150
4	47	-90	38	94	32	15	160
5	45	-90	55	94	30	15	150
6	34	-90	81	94	22	12	110
7	31	90	68	94	21	10	105
8	39	90	37	94	26	13	130
9	48	90	14	94	32	16	160
10	50	-90	46	94	30	20	75
11	41	-90	65	94	26	15	65

Note: the horizontal angle is the angle between the drilling direction and the center line of the roadway. Elevation angle is the angle between the drilling direction and the horizontal line of the roadway.