Prediction of Fracture Evolution and Groundwater Inrush from Karst Collapse Pillars in Coal Seam Floors: A Micromechanics-Based Stress-Seepage-Damage Coupled Modeling Approach

Table 1

Mechanical and hydraulic parameters for the strata in the numerical model.

Lithology	Elastic modulus; , (GPa)	Poisson’s ratio	Initial microcrack length; , (mm)	Fracture toughness; , (MPa m^1/2)	Critical microcrack length; , (mm)	Initial permeability; , (m^2)
Overlying strata	9.5	0.25	15	4.5	45
Coal seam	1.5	0.30	25	1.5	75
Aquiclude	6.0	0.25	10	4.5	30
Aquifers	9.5	0.25	15	4.5	45