Ground Vibration Intensity Calculator

Peak particle velocity is the maximum speed at which a point of ground moves as a stress wave passes through it, not the speed of the wave itself. Blast engineering settled on this quantity because field studies found that cosmetic cracking of plaster and drywall correlates far better with particle velocity than with displacement or acceleration. The attenuation law joins two ideas: energy scales with the charge weight W detonated within a single delay interval, and amplitude decays with distance D through geometric spreading plus inelastic absorption. Dividing D by the square root of W gives the scaled distance, a scaling suited to the long cylindrical charge columns of bench blasting; cube-root scaling suits compact concentrated charges. In metric units K commonly falls between about 500 and 5000, and B between -1.2 and -1.8, with -1.6 a frequent default. Frequency governs the damage threshold because low-frequency ground motion near the 4 to 12 Hz natural frequencies of house walls and floors produces resonant amplification. The frequency-dependent limits applied here follow USBM practice: 12.7 mm/s below 10 Hz, 19 mm/s from 10 to 40 Hz, and 50.8 mm/s above 40 Hz for residential structures. Germany uses DIN 4150-3, which drops to about 3 mm/s for sensitive historic buildings. The main limitation is that K and B are not universal constants; they must be regressed from at least twenty to thirty monitored shots at the site, and the fitted curve is only a median. Individual shots routinely scatter by a factor of two either side, so compliance work should use the upper 95 percent confidence line rather than the best-fit prediction.

Systematic ground vibration limits grew out of United States Bureau of Mines research beginning in the 1930s. Bulletin 442, Seismic Effects of Quarry Blasting by Thoenen and Windes, appeared in 1942 and set out early damage criteria based on an energy ratio derived from acceleration and frequency. Through the 1950s several competing criteria circulated, some using displacement and some using acceleration, and quarry operators faced inconsistent regulation across jurisdictions. In 1962 Duvall and Fogelson published Report of Investigations 5968, reviewing the accumulated damage data and proposing a particle velocity threshold of 2 inches per second, equal to 50.8 mm/s, as the point at which cosmetic damage becomes likely. That report also helped establish scaled distance as the working normalization for comparing blasts of different size. Nicholls, Johnson and Duvall consolidated the field in Bulletin 656 in 1971. The decisive study came in 1980, when Siskind, Stagg, Kopp and Dowding published Report of Investigations 8507, based on instrumented monitoring of homes near active blasting operations. Their key finding was that a single velocity limit was inadequate, because low-frequency vibration excites structural resonances that higher-frequency vibration does not. The resulting frequency-dependent criterion was adopted into United States surface mining regulations administered by the Office of Surface Mining Reclamation and Enforcement, and comparable frequency-dependent standards were later written into DIN 4150-3 in Germany and BS 7385 in Britain. Electronic detonators, commercialized from the 1990s, gave blasters the millisecond timing precision needed to keep charge weight per delay low.