Research on Optimal Design of Pressure Relief Blasting Parameters of Middle Rock Pillar in Near Vertical Coal Seam

Table 1

Summary of measurement results of physical and mechanical property parameters of +500 m horizontal coal and rock samples.

Coal and rock parameters	B3 coal seam	B2 coal seam	B3 coal seam floor rock	B2 coal seam roof rock
Apparent density (kg/m³)	1284	1253	2478	2692
Internal friction angle (°)	24.08	27.54	66.44	38.42
Cohesion (MPa)	2.4	1.7	5.4	6.9
Modulus of elasticity (GPa)	0.204	0.209	1.674	2.343
Poisson’s ratio	0.21	0.19	0.23	0.22