Optimization and Practice for Partition Pressure Relief of Deep Mining Roadway Using Empty-Hole and Deep-Hole Blasting to Weaken Coal

Table 4

Physical-mechanical parameters.

Lithology	Density (kg/m^3)	Elastic modulus (GPa)	Poisson’s ratio	Internal friction angle (°)	Cohesion (MPa)
Fine sandstone	2600	38.8	0.22	33.2	11.7
Medium sand	2650	63.2	0.18	36.2	28.0
Mudstone	2500	18.9	0.28	43.2	9.7
Coal	1400	6.7	0.22	25.2	6.8