Coal and Gas Comining in the High-Gas Detong Mine, China: Analytical and Numerical Parameter Optimization of Gas Extraction Boreholes

Table 2

Calculation formula parameter value.

Symbol	Parameter	Value	Unit
H	Mining height	5	m
λ	Gas gushing coefficient	1.2
W0	Initial gas content of coal seam	11.7	m^3·t^−1
Wc	Residual gas content	3.95	m^3·t^−1
m	Mining layer thickness	5	m
	Mining velocity of workface	4.1 × 10^−3	m·min^−1
q0	Gas gushing intensity of the coal wall	0.0401	m^3·(m^2·min) ^−1
l1	Workface length	185	m
l1	Strike length of goaf	200	m