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Geologic factors affecting vibration from surface mine blasting.

Reil JW; Anderson DA; Ritter AP; Clark DA; Winzer SR

Minneapolis, MN: U.S. Department of the Interior, Bureau of Mines, Contract H0222009, 1985 Sep; :1-191

https://ntrl.ntis.gov/NTRL/dashboard/searchResults/titleDetail/PB86175858.xhtml

10005059

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.

Mining research; Blasting; Fragmentation; Strain gages; Vibration; Surface mining

19850901

CP; Final Contract Report

1985

PB86-175858

A11

OFR 33-86; Contract-H0222009

TCRC

Minneapolis, MN: U.S. Department of the Interior, Bureau of Mines, Contract H0222009

MN; PA

Vibra-Tech Engineers, Inc.