Mechanism and Evolution Control of Wide Coal Pillar Bursts in Multithick Key Strata

Table 4

Physical and mechanical parameters of coal and rock.

Lithology	Density (kg/m^3)	Bulk modulus (GPa)	Shear modulus (GPa)	Friction angle (°)	Tensile strength (MPa)
Coal	1832	1.25	1.3	42.02	1.77
Sandy mudstone	2321	4.04	3.03	26.10	4.34
Medium sandstone	2294	4.76	2.99	27.23	3.32
Coarse sandstone	2343	5.38	3.54	31.53	4.13
Fine sandstone	2352	13.63	4.88	30.82	5.67
Silstone	2355	4.17	2.63	21.31	3.62