A Preliminary Study on the Design Method for Large-Diameter Deep-Hole Presplit Blasting and Its Vibration-Isolation Effect

Table 2

Cast-blasting parameters.

Parameter	Symbol	Unit	Value
Hole diameter	d	mm	310
Minimum burden		m	6.0～6.5
Spacing	a	m	9～12
Array pitch	b	m	7～9
Hole angle	β	∘	65
Powder factor	q	kg/m^3	0.7～0.8
Stemming length	l	m	6～8
Delay between holes	tk	ms	9～20
Delay between rows	tp	ms	100～200
Delay in hole	tn	ms	400～600