Study on Pressure Relief Technology of High-Pressure Water Jet of Residual Coal Pillar in Overlying Goaf in Close Seam Mining

Table 2

Coal pillar width direction drilling layout parameters.

Borehole number	Starting point of drilling	Azimuth of drilling (°)	Elevation angle of drilling (°)	Length of drilling hole (m)	Number of slots	Gap between slots (m)
1	(−1.0, 0)	90	36	49.70	2	4
2	(−0.5, 0)	90	35	51.70	2	4
3	(0, 0)	90	33	53.80	3	4
4	(0, 0.5)	90	28	63.50	2	4
5	(0, 1.0)	90	27	66.40	2	4
6	(0, 1.5)	90	27	69.30	3	4