Coupling Technology of Deep-Hole Presplitting Blasting and Hydraulic Fracturing Enhance Permeability Technology in Low-Permeability and Gas Outburst Coal Seam: A Case Study in the No. 8 Mine of Pingdingshan, China

Table 1

Mechanical parameters of coal and rock formations.

Classification	Elastic modulus (GPa)	Poisson’s ratio	Internal friction angle (°)	Cohesion (MPa)	Density (kg/m^3)
Coal	2	0.35	20	0.3	1350
Rock	10	0.3	25	2	2500