Strutt|Vibration|Blasting|Airblast calculates the estimated airblast overpressure given the distance from the explosive charge (m) and the mass of the explosive charge (kg) and inserts the result into the active row.
Strutt implements the formula as:
`P = K_a*(r/Q^(1//3))^a`
`P` is the calculated pressure, kPa
`Q` is the mass of the explosive charge, kg
`r` is the distance from the explosive charge, m
`K_a` is the site constant
`a` is the site exponent
AS2187.2-2006 recommends using a site exponent `a` of -1.45 and a site constant `K_a` of 516 for unconfined surface charges, in situations that are not affected by meteorological conditions.
For confined blasthole charges, when using a site exponent `a` of -1.45, the site constant `K_a` is commonly in the range 10 to 100.