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Geologic Factors Affecting Vibration from Surface Mine Blasting.

Authors
Reil-JW; Anderson-D; Ritter-A; Et Al
Source
NTIS: PB/86-175858 :204 pages
Link
NIOSHTIC No.
10005059
Abstract
A test series of small, precisely controlled and thoroughly monitored production blasts was conducted at two quarries. In each series, all variables except delay were kept constant, as much as practically possible. The first aim of the study was to determine the effect of local geology on ground vibration. The second aim was to test several hypotheses relating the effect of millisecond delay intervals to fragmentation and ground vibration. A resonant frequency of ground vibration was shown to be related to the thickness of the overburden, in accord with a model proposed by gupta. Since the overburden geology creating this resonant vibration cannot usually be changed, two methods were tested to choose delays such that blast vibrations would destructively interfere. These methods were shown to be effective in modifying both the peak particle velocity and response spectra of ground vibration. The delay interval chosen also affects fragmentation, primarily in massive rock, with an optimum relief between holes of 2 ms/ft. Strain gauge records indicate a possible mechanism consistent with this information.
Publication Date
19850101
Document Type
CP; Final Contract Report;
Fiscal Year
1985
NTIS Accession No.
PB86-175858
NTIS Price
A11
Identifying No.
OFR 33-86
NIOSH Division
TCRC;
Source Name
NTIS: PB/86-175858
Performing Organization
Vibra-tech Engineers, Inc.
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