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Airblast-overpressure Levels from Confined Underground Protection Blasts.

Authors
Olson-JJ; Fletcher-LR
Source
NTIS: PB 205 501 :24 pages
Link
NIOSHTIC No.
10001679
Abstract
The Bureau of Mines recorded and analyzed overpressure levels for three production blasts at the White Pine Copper Mine, upper Michigan, to obtain representative data from single-heading blasts in a long, straight haulageway and to estimate the damage potential inherent in production blasts fired in close proximity to underground structures. Commercial pressure gages with a flat response to 1 khz were used with an fm tape recorder to record the overpressures from one dynamite and two ammonium nitrate-fuel, oil, 500-msec production blasts having zero-delay charge weights of about 75 lb (34 kg). The recorded waveforms from the underground blasts (1) were more complex than the typical free-air wave, (2) were of larger duration, and (3) had numerous secondary arrivals owing to reflections from the ribs and roof. The waveforms showed that the zero-delay charges produced the only high overpressures.
Publication Date
19710101
Document Type
IH; Report of Investigations
Fiscal Year
1971
NTIS Accession No.
PB-205501
NTIS Price
A03
Identifying No.
RI 7574
NIOSH Division
TCRC;
Source Name
NTIS: PB 205 501
State
MI;
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