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Comparative Study of Blasting Vibrations from Indiana Surface Coal Mines.

Authors
Siskind-DE; Crum-SV; Otterness-RE; Kopp-JW
Source
MISSING :41 pages
Link
NIOSHTIC No.
10006966
Abstract
The U.S. Bureau of Mines performed a comparative study of nine sites at eight surface coal mines to determine if the presence of near- surface underground abandoned workings resulted in the generation of adverse long-duration, low-frequency blast vibrations. Six of the nine sites had underlying workings, and two had thick layers of low- velocity unconsolidated surface material. Extended seismic arrays were used to identify the vibration characteristics within a few tens of feet of the blasts and also as modified by the propagating media at distances over 1 mile. Production blasts and specially fired single-charge blasts allowed the determination of natural ground frequency and the influence of initiation delay timing. Vibration amplitudes from the production blasts at all sites exceeded historical norms, particularly at the greater distances. This contrasts with the near-normal results from single-charge blasts. Apparently, between-hole time delays were insufficient to separate vibrations from adjacent charges for the low-frequency waves present. Single-charge tests showed that the propagating media produced low-frequency, ground-roll-type surface waves at nearly all sites. Large blasts at such sites could produce an unacceptable risk of vibration-induced cracks in nearby structures.
Publication Date
19890101
Document Type
IH; Report of Investigations;
Fiscal Year
1989
NTIS Accession No.
NTIS Price
Identifying No.
RI 9226
NIOSH Division
TCRC;
Source Name
MISSING
State
IN;
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