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Effects of Millisecond-delay Intervals on Vibration and Airblast from Surface Coal Mine Blasting.

Authors
Kopp-JW; Siskind-DE
Source
MISSING :44 pages
Link
NIOSHTIC No.
10005186
Abstract
A major concern with blasting at surface mines is generation of ground vibrations and airblast and their effects on nearby residences. This Bureau of Mines report looks at the use of millisecond delays in blast design and their effect on the resulting ground vibrations and airblast. A total of 52 production blasts were instrumented and monitored at a surface coal mine in southern Indiana. Arrays of seismographs were used to gather time histories of vibrations and airblast. The data were analyzed for peak values of vibration and airblast and for frequency content. Various delay intervals were used within and between rows of blastholes. Delay intervals within rows were 17 and 42 milliseconds (ms) and those between rows ranged from 30 to 100 ms; these intervals are equivalent to 0.5 and 1.3 Ms/ft within rows and 1.2 to 4.3 Ms/ft between rows. Subsonic delay intervals within rows reduced airblast by 6 db. Large delay intervals between rows reduced the amplitude of ground vibrations; their frequency depended primarily upon the geology of the minesite.
Publication Date
19860101
Document Type
IH; Report of Investigations
Fiscal Year
1986
NTIS Accession No.
NTIS Price
Identifying No.
RI 9026
NIOSH Division
TCRC;
Source Name
MISSING
State
IN;
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