Study of the Fracture Law of Overlying Strata under Water Based on the Flow-Stress-Damage Model

Table 1

Mechanical parameters of the main strata.

Lithology	Bulk modulus (GPa)	Shear modulus (GPa)	Cohesion (MPa)	Tensile strength (MPa)	Friction (°)
Mudstone	0.6	0.32	0.5	0.6	28
Fine sandstone	1.63	1.2	2.5	1.1	32
Medium sandstone	1.6	1.14	2.2	1.0	31
Siltstone	1.87	1.12	2.0	1.0	30
Coal	0.8	0.14	0.3	0.5	26