Air-Blast Suppression as a Function of Explosive-Charge Burial Depth

Abstract

The blast wave from buried explosions consists primarily of a pulse induced by the ground shock followed by another pulse when the explosive gases are vented to the atmosphere. The latter pulse provides the dominant contribution for the shallower burial depths. Air-blast measurements made along the ground surface for 46 chemical explosive and 7 nuclear explosive detonations have shown the peak overpressure of the ground-shock-induced pulse to be about the same for chemical and nuclear explosions in basal rock as for chemical explosions in alluvial soil. The ground-shock-induced pulse has not been observed for nuclear explosions in soil. The peak overpressure from venting gases is about equal for chemical explosives in basalt rock and alluvial soil. Peak overpressures are higher for nuclear explosions in soil, in part because the cavity pressures at the time of venting are higher; peak overpressures are lower for nuclear explosions in rock, presumably because less gas is formed and because the pulse from venting gas coincides with the negative phase following the ground-shock-induced pulse, thus reducing overpressure amplitude. Measurements have been made over a sufficiently large range of charge burial depths that a pattern of air-blast suppression with charge burial can be presented.