Coal and Gas Comining in the High-Gas Detong Mine, China: Analytical and Numerical Parameter Optimization of Gas Extraction Boreholes

Table 1

Physical and mechanical properties of rock strata.

Stratum	Buried depth, m	Thickness, m	Density, kg·m^−3	Bulk modulus, GPa	Shear modulus, GPa	Internal friction angle	Cohesion, MPa	Tensile strength, MPa
Argillaceous sandstone	0	100	2790	8.6	4.65	34	4.31	1.8
Coarse sandstone	−100	178	2860	2.9	2.5	32	2.1	2.1
Siltstone	−278	54	2540	5.38	2.74	35	2.23	0.6
Medium grained sandstone	−332	35	2650	7.2	3.53	35	3.26	2
Conglomerate rock	−367	10	2610	4.55	2.58	32	2	2.4
Coal	−377	5.3	1400	1.19	0.37	23	0.8	0.5
Siltstone	−382.3	3.4	2580	5.61	2.35	36	2.15	0.7