Study on the Key Factors of Terminal Mining Line Layout in Repeated Mining of Close-Distance Thick Coal Seams

Table 1

Mechanical parameters of coal and rock mass in calculation model.

Layer	Natural density (kg/m^3)	Shear modulus (GPa)	Bulk modulus (GPa)	Cohesion (MPa)	Internal friction angle (°)	Tensile strength (MPa)
Overlying strata	2500	7.80	9.00	2.40	32	1.30
Coarse sandstone	2580	8.40	11.23	2.40	32	1.50
Fine sandstone	2612	8.24	11.79	2.83	33	1.60
Siltstone	2300	4.26	5.79	1.53	31	0.80
1# coal seam	1550	3.36	4.51	1.00	27	0.30
Fine sandstone	2612	8.24	11.79	2.73	31	1.50
Medium-fine sandstone	2580	7.90	9.30	2.20	32	1.30
Kaolinite rock	2450	6.89	8.76	2.10	30	1.20
Conglomerate	2520	7.54	9.23	2.30	31	1.40
Carbonaceous mudstone	2360	4.35	5.87	1.80	29	1.20
2# coal seam	1550	3.36	4.51	1.00	27	0.30
Carbonaceous mudstone	2360	4.35	5.87	1.80	29	1.20
Kaolinite rock	2450	6.89	8.76	2.30	30	1.40
Medium-fine sandstone	2580	7.90	9.30	2.40	32	1.30