Study on Presplitting Blasting the Roof Strata of Adjacent Roadway to Control Roadway Deformation

Table 1

Mechanical parameters of the floor.

Mechanical parameter	Hard rock	Medium-hard rock	Soft rock	Extremely soft rock
Compressive strength (MPa)	≥60	30∼60	15∼30	≤15
Cohesion (MPa)	≥6.5	4.0∼6.5	2.5∼4.0	≤2.5
Internal friction angle (°)	≥38	30∼38	20∼30	≤20
Strength of extension (MPa)	≥4.2	3.2∼4.2	2.2∼3.2	≤2.2
Density (g·m^−3)	≥2.4	2.0∼2.4	1.6∼2.0	≤1.6