Control of the Internal and External Staggered Distance of Coal Mining Face to the Water-Conducting Fissures in the Overlying Strata of the Near Coal

Table 3

The mechanical parameters of the rock joints.

Rock formation	Normal stiffness (MPa)	Tangential stiffness (MPa)	Cohesion (MPa)	Joint penetration factor (Pa^−1·s^−1)	Initial gap (mm)	Residual gap (mm)
Coal seam	1600	1100	0.313	166.7	0.5	0.1
Silt sandstone	7600	5200	0.800	166.7	0.5	0.1
Coarse-grained sandstone	7900	5600	0.688	166.7	0.5	0.1
Medium-grained sandstone	7500	5500	0.712	166.7	0.5	0.1
Fine-grained sandstone	8800	6600	0.690	166.7	0.5	0.1
Sandy mudstone	6400	4500	0.375	101.5	0.5	0.1
Loess	9000	7900	0.311	15	0.1	0.1
Loose layer	2200	1300	0.100	300	3.0	0.1