Prevention Technology for Strong Mine Pressure Disaster in the Hard-Roof Large-Mining-Height Working Face

Table 1

Physical and mechanical parameters of various strata.

Stratum	Density (kg·m^−3)	Bulk modulus (GPa)	Shear modulus (GPa)	Cohesive force (MPa)	Internal friction angle (°)	Tensile strength (MPa)
Overburden	2400	9.33	5.60	5.5	35	3.0
Sandstone grit	2400	12.68	8.73	6.8	35	5.5
Mudstone	2400	3.1	3.5	5.0	40	1.5
Sandy mudstone	2300	10.95	7.54	5.0	33	4.2
Fine sandstone	2500	18.49	15.04	15.7	40	9.2
Coal seam	1400	1.95	1.31	4.2	38	1.3
Floor	2400	11.83	8.88	8.5	35	6.0