ABSTRACT
The set of air column in the blast hole is similar to the energy storage component in hydraulic vibration impact system, which is gas accumulator. The main principle is the use of large energy storage capabilities of the gas storage chamber to absorb impact, eliminate pulsation and recover energy. When explosive column exploded in the hole, the air columns placed on the bottom and top of the hole absorbs the peak impact energy, and convert into smooth transitions clipping compression energy, to improve energy efficiency, reduce peak vibration. Assuming the dynamite in blast hole is the same nature, density is uniform and continuous distribution, therefore the pulse of initial pressure and the explosion time can be calculated:
P K
= ⋅
+ ⋅
+
1 2
1 1
1 1
2ρ
(1)
t D
I l
2 2
( )1K + ( )a+1
ρ (2)
Where Pm = explosion pulse of initial pressure; K = explosion products isentropic coefficient, K = 3; ρo = explosive density; D = explosive detonation velocity; T = duration of action; I = blasting impulse; la = air column length; and lc = charge length.
