Disastrous Mechanism of Water Discharge in Abandoned Gob above the Stope in Mining Extra-Thick Coal Seam

Table 2

The percolation mechanical parameters of joints.

Rock strata	f (°)	jperm (Pa^-1·s^-1)	azero (m)	ares (m)
Coal seam	30	83	0.0001	0.00001
Sandy mudstone	32	100	0.0001	0.00001
Siltstone	30	128	0.0002	0.00003
Fine sandstone	30	143	0.0003	0.00004
Medium sandstone	33	178	0.0002	0.00003
Coarse sandstone	32	246	0.0004	0.00006