Parameters

Coal bed

Top/Bottom bed

Intrinsic permeability, $k_0$, mD

1.462

0.146

Porosity, $\phi$

0.06

0.02

Internal expansion coefficient, $C_{pp}$, $MP{a}^{-1}$

0.01

0.01

Internal contraction coefficient, $C_{pc}$, $MP{a}^{-1}$

0.01

0.01

Biot coefficient, α

0.33

0.33

Mass density, $\rho$, $Kg/m^3$

1200

2500

Solid skeleton elasticity modulus, E_d, Gpa

9

11.56

Solid matrix elasticity modulus, E_s, Gpa

13.42

15

Poisson's ratio, v,

0.3

0.3

Solid skeleton compression strength limit, ${\sigma }_c$, Mpa

7.7

16.25

Ratio of compression to tension strength, γ

15

15

Tensile strain threshold, ${\epsilon }_{t0}$, 10^-3

0.0085

0.015

Final tensile strain, ${\epsilon }_{t\mathrm{u}}$, 10^-3

0.085

0.65

Thickness of localized damage band, $\delta$, mm

19

5