Roadway Surrounding Rock under Multi-Coal-Seam Mining: Deviatoric Stress Evolution and Control Technology

Table 1

Mechanical parameters of rock strata and coal seams.

Lithology	Bulk modulus (GPa)	Shear modulus (GPa)	Cohesion (MPa)	Tensile strength (MPa)	Internal friction angle (°)	Density (g/cm^3)
Medium sandstone	7.50	4.10	1.60	6.51	34	2.70
Fine sandstone	5.32	2.84	1.46	5.54	31	2.65
Siltstone	5.82	3.14	1.30	5.70	32	2.55
No. 7-3 coal seam	3.75	1.87	1.10	0.95	27	1.40
Gritstone	9.32	6.50	1.86	7.58	35	2.82
No. 7-4 coal seam	3.75	1.87	1.10	0.95	27	1.40
Sandy mudstone	4.28	2.30	1.20	1.19	28	2.36
No. 11 coal seam	3.75	1.87	1.10	0.95	27	1.40