Mechanism and Control of Water–Rock Coupling-Induced Disaster when Mining below the Unconsolidated Confined Aquifer

Table 1

Physical mechanical parameters of the block.

Lithology	(m)	(kg/m^−3)	(GPa)	(GPa)	(MPa)	(°)
Middle water-resisting layer	50	1800	2.70	1.30	0.50	15
Lower confined aquifer	18	2000	1.20	0.60	0.20	10
Lower water-resisting layer	27	1800	2.70	1.30	0.50	15
Overlying strata	20	2550	7.35	4.63	3.04	42
Main roof	8	2650	16.04	5.62	3.47	43
Coal seam	4	1400	1.90	0.93	0.80	27
Immediate floor	3	2500	3.94	2.60	1.68	30
Main floor	5	2600	7.94	6.31	2.93	35
Underlying strata	15	2600	10.92	3.72	2.10	43

: thickness; : density; : bulk modulus; : shear modulus; : cohesion; and : friction angle.