Study on the Technology of Enhancing Permeability by Millisecond Blasting in Sanyuan Coal Mine

Table 4

Drilling parameters.

Name	Angle with roadway	Elevation	Drilling depth	Visible coal length	Pressure	Distance from the blasting hole
Value 1	90	+40	25	7.5	0.24	2.25
Value 2	90	+40	25	7.5	0.26	2.25
Unit	°	°	m	m	MPa	m