A Mechanical Model of the Overlying Rock Masses in Undersea Coal Mining and a Stress-Seepage Coupling Numerical Simulation

Table 1

Parameters of coal and rock.

Lithology	Density (kg/m^3)	Elastic modulus (MPa)	Poisson's ratio	Internal friction angle (°)	Cohesion (MPa)	Tensile strength (MPa)
Aquifer 2	2.00	10	0.31	34.6	0.13	0.002
Aquifuge	2.01	160	0.28	33.4	0.71	0.11
Aquifer 1	2.02	2300	0.24	32.3	0.92	0.21
Cmudstone aquifer	2.30	1400	0.13	36.7	1.71	0.67
Marl aquifer	2.00	1200	0.21	30.4	1.42	0.89
Roof 3	2.60	75	0.13	36.1	0.33	0.08
Interbedded aquifer	2.50	1000	0.30	28.5	1.71	0.76
Roof 2	1.80	800	0.16	37.8	1.62	0.48
Coal-oil shale aquifer	1.80	900	0.28	40.4	2.10	0.55
Roof 1	2.02	200	0.35	26.2	0.32	0.02
Immediate roof	1.80	350	0.26	26.7	2.01	0.42
Coal	1.50	40	0.34	29.6	0.51	0.45
Floor	2.40	1900	0.32	33.1	2.10	1.52