An “air blast” is a shockwave generated by an explosion, characterized by a sudden rush of air or a pressure wave. It can be audible (high-frequency, like noise) or sub-audible (low-frequency, like concussion). Air blasts can be caused by various explosions, including those in mining or construction.
Here’s a more detailed explanation:
Source:
Air blasts originate from the rapid expansion of gases and the movement of rock and air during an explosion.
Pressure Wave:
The shockwave travels outward from the source, creating pressure fluctuations in the surrounding air.
Audible vs. Sub-audible:
The audible portion (20-20,000 Hz) is what we perceive as noise, while the sub-audible portion (below 20 Hz) is often referred to as concussion.
Negative Effects:
Air blasts can cause vibrations, cracking of windows or plaster, and even damage to structures, depending on the pressure.
Controlling Airblast:
Proper stemming (packing materials to contain gases) and burden (distance of explosives from the blast face) can help minimize airblast effects.
Related Terms:
“Air overpressure” is another term for the pressure wave associated with an air blast. “Concussion” refers to the sub-audible portion of the air blast.