Stress Distribution and Optimum Spacing Determination of Double-Withdrawal-Channel Surrounding Rocks: A Case Study of Chinese Coal Mine

Table 2

Mechanical parameters of rock formation.

Parameter lithology	Density (kg/m^3)	Bulk modulus (GPa)	Shear modulus (GPa)	Internal friction angle (°)	Cohesion (MPa)	Tensile strength (MPa)
Sandy mudstone	2300	0.73	0.75	32	2.5	1.65
Fine-grained sandstone	2500	2.53	3.78	33	3.0	1.75
Sandy mudstone	2400	3.8	1.8	28	2.1	1.7
2-2 middling	1350	0.16	0.4	25	1.2	1.2
Sandy mudstone	2400	3.2	2.6	27	1.3	1.1
Fine-grained sandstone	2500	2.53	3.78	31	2.5	1.7
Sandy mudstone	2400	3.2	2.6	27	1.3	1.1
3-1 middling	1400	1.19	0.38	28	1.6	1.03
Sandy mudstone	2600	3.9	1.9	31	1.5	1.3
Fine-grained sandstone	2500	2.53	3.7	31	2.5	1.7
4-1 coal	1500	3.48	1.61	34.45	1.43	0.92