Numerical Analyses of the Major Parameters Affecting the Initiation of Outbursts of Coal and Gas

List of Symbols bi Body force per unit mass (N/m ) C Average matrix gas concentration (m/m) g Gravitational acceleration (m/s) I Unit tensor (dimensionless) DJ 0 1 The first stress invariant (N/m) K Absolute permeability (md) krn Relative permeability (dimensionless) P Pore pressure (Pa) PL Langmuir pressure (Pa) qg The well flowrate for gas (m /day) qw The well flowrate for water (m /day) qm Diffusion and desorption of gas between the matrix and the cleat (m/day) Rsw Gas solubility in water (m /m) s Gas or water shrinkage factor (m/m) S Degree of saturation (dimensionless) v Velocity (m/s) V Volume of gas adsorbed at pressure Pg (m ) VL Langmuir volume (m /m) Vm Bulk volume of a matrix element (m ) rij Stress tensor (N/m ) e Strain tensor (dimensionless) a Biot’s effective stress parameter ln Viscosity (Pa s) U Effective fracture porosity (dimensionless) s Sorption time (day) q Mass per unit volume of the medium (kg/m)