Increasing Permeability of Coal Seam and Improving Gas Drainage Using a Liquid Carbon Dioxide Phase Transition Explosive Technology

Table 3

Numerical simulation parameters.

	Parameters	Values
Coal	Initial porosity φ0	0.065
	Initial permeability k0 (m^2)	3.90 × 10^−16
	Elastic modulus E (GPa)	1.30
	Kronecker symbol δij	1.00
	Klingberg coefficient m (Pa)	7.60 × 10^5
	Poisson’s ratio	0.36
	Shear modulus G (GPa)	0.52
	Ash content A	0.14
	Moisture content B	0.04
	Adsorption constant a (m^3/kg)	14.5
	Tensile strength σt (MPa)	0.42
	Compressive strength σc (MPa)	3.40
	Friction angle (°)	29
	Adsorption constant b (MPa^−1)	0.75
	Coal density ρc (kg/m^3)	1400
	Biot coefficient	1
Sandy mudstone of roof	Tensile strength σt (MPa)	0.61
	Compressive strength σc (MPa)	7.78
	Friction angle (°)	32
	Elastic modulus E (GPa)	4.34
	Poisson’s ratio	0.28
Mudstone of floor	Tensile strength σt (MPa)	0.47
	Compressive strength σc (MPa)	6.33
	Friction angle (°)	30
	Elastic modulus E (GPa)	2.85
	Poisson’s ratio	0.35
Methane gas	Viscosity μ (Pa·s)	1.10 × 10^−5