The Mechanism and Application of Deep-Hole Precracking Blasting on Rockburst Prevention

Table 2

Classification of bursting proneness of coal.

Classification	Type I	Type II	Type III
Bursting proneness	None	Weak	Strong
Indexes
Duration of dynamic fracture ()/ms	> 500	50 < ≤ 500	≤ 50
Elastic strain energy index ()	< 2	2 ≤ < 5	≥ 5
Bursting energy index ()	< 1.5	1.5 ≤ < 5	≥ 5
Uniaxial compressive strength ()/MPa	< 7	7 ≤ < 14	≥ 14