Blast Vibration Safe Distance Calculator
Estimate the minimum standoff distance at which a blast's ground vibration should stay within a chosen peak particle velocity (PPV) limit, using the Devine scaled-distance law. Enter the maximum instantaneous charge per delay and a PPV limit, and optionally a distance to see the predicted vibration there. This is a vibration screening aid only — it does not set personnel or flyrock exclusion zones.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the maximum instantaneous charge per delay W in kilograms (the largest mass of explosive detonating on any single delay, not the total shot).
- Set the PPV limit in mm/s (10 mm/s is a common guide for nearby structures; your site limit may differ) and, if you have site-derived values, adjust the site constant K and attenuation exponent β.
- Optionally enter a distance D to a receiver to read the scaled distance and the predicted PPV at that point, then compare it with your limit.
How it works
The Devine equation models peak particle velocity as PPV = K · (D / √W)^(−β), where D is distance in metres, W is the charge per delay in kilograms, K is a site constant and β is the attenuation exponent. The quantity SD = D / √W is the scaled distance. Setting PPV equal to your limit and solving for distance gives the minimum safe distance D_safe = √W · (K / PPV_limit)^(1/β). Larger charges per delay and lower attenuation push the safe distance out. K and β are properties of a particular site and blast geometry and should be back-calculated from monitored trial blasts rather than assumed.
Worked example
Worked example. For W = 50 kg per delay, a 10 mm/s limit, K = 1140 and β = 1.6: D_safe = √50 × (1140 / 10)^(1/1.6) = 7.071 × 19.30 = 136.47 m. Checking a receiver at D = 100 m from a 50 kg charge gives SD = 100 / √50 = 14.142 m/√kg and PPV = 1140 × 14.142^(−1.6) = 16.45 mm/s — above the 10 mm/s limit, so 100 m is too close for that limit.
Common mistakes
- Using the total charge in the shot instead of the maximum instantaneous charge per DELAY — the delays are what separate the vibration pulses, so W is per delay.
- Treating the default K = 1140 and β = 1.6 as fact: they are generic placeholders. Real predictions need K and β regressed from monitored blasts at your site.
- Assuming this distance is the exclusion zone. It addresses ground vibration only — flyrock, air-overpressure and personnel exclusion are set by the blast management plan and regulator.
Frequently asked questions
What PPV limit should I use?
It depends on what you are protecting and the applicable standard or approval condition — residential structures, heritage buildings, fresh concrete and sensitive equipment all have different limits. Use the limit set by your blast management plan, approval or the relevant standard, not a generic number.
Does a safe vibration distance mean it is safe to stand there?
No. This tool only estimates ground vibration. Flyrock and air-blast can travel far beyond the vibration-safe distance. Personnel exclusion zones must come from the documented blast management plan and a competent shotfirer, in line with AS 2187 and the regulator.
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Tip: Enter any known values to calculate the remaining results.
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