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Initiation Timing Influence on Ground Vibration and Airblast.

Authors
Kopp-JW
Source
Surface Min 1987 1:167-172
Link
NIOSHTIC No.
10007524
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 two rows were 17 and 42 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 mine site.
Publication Date
19870101
Document Type
OP;
Fiscal Year
1987
NTIS Accession No.
NTIS Price
Identifying No.
OP 45-90
NIOSH Division
TCRC;
Source Name
Surface Min., V. 1, 1987, PP. 167-172
State
IN;
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