Research of the Backfill Body Compaction Ratio Based on Upward Backfill Safety Mining of the Close-Distance Coal Seam Group

Table 2

The detailed physical and mechanical parameters.

Serial number	Lithology	Bulk modulus (GPa)	Shear modulus (GPa)	Density (g/cm^3)	Cohesion (MPa)	Tensile strength (MPa)	Friction angle (°)
1	Gravelly coarse sandstone	12.04	5.32	2.85	4.61	4.35	42.3
2	Sandy mudstone	6.83	2.89	2.73	3.34	1.86	34.8
3	Siltstone	8.82	4.84	2.65	3.20	2.47	37.3
4	Fine-grained sandstone	7.87	3.34	2.63	3.65	2.19	37.1
5	4 coal, 4 upper coal	2.35	1.42	1.33	2.99	1.10	36.2
6	Mudstone	3.64	2.10	2.36	3.20	1.50	34.8
7	Aluminum mudstone	1.68	1.14	2.56	5.20	1.10	33.8