Study of the mechanisms of fragmentation and vibration in blasting operations. Final report. [Single, dual and 5 hole shots with delays]
A two-part study was conducted to determine the factors affecting the frequency and amplitude of blast-induced ground vibration. One part, conducted by the Photomechanics Laboratory of the Department of Mechanical Engineering of the University of Maryland, simulated and measured the surface displacements due to small explosive charges detonated on the surface of rock and a rock analog. The other part, conducted by Martin Marietta Laboratories, determined the effect of changing delay parameters on blast vibrations in precisely controlled small quarry blasts. The University of Maryland study measured the surface displacements due to explosive charges with holographic interferometry. the Martin Marietta study consisted of a test series of blasts in an operating quarry to determine the effect of precisely controlled delay timing on the frequency and amplitude of ground vibration. An aerial survey was conducted to produce a topographic map of the area to be studied, and reconnaissance geological mapping was carried out to determine the gross aspects of the deposit. Preliminary analysis of seismograph data indicated that dual-hole shots with short time delays generated seismograms which were indistinguishable from single-hole shot seismograms. Also, linar superposition of single-hole seismograms, appropriately delayed, would not reproduce the records generated by the multi-hole blasts. These results were not expected. Examination of the strain-gage records indicated that there was probably some interaction of strain pulses for the shorter delay shots, and that the interaction was non-linear with distance from the borehole. This non-linear interaction may be the cuase of the unexpected results. Five-hole shots show more complicated seismograms, which are a combination of the results of the two-hole shots and the local ground response.
- Research Organization:
- Martin Marietta Labs., Baltimore, MD (USA)
- DOE Contract Number:
- AC01-80ET14357
- OSTI ID:
- 6517446
- Report Number(s):
- DOE/ET/14357-T6; ON: DE83006069
- Country of Publication:
- United States
- Language:
- English
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45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
58 GEOSCIENCES
EXPLOSIVE FRACTURING
BLAST EFFECTS
MECHANICAL VIBRATIONS
SEISMIC EFFECTS
SURFACE MINING
COAL MINING
EXPERIMENTAL DATA
FRAGMENTATION
INTERACTIONS
COMMINUTION
DATA
FRACTURING
INFORMATION
MINING
NUMERICAL DATA
012000* - Coal
Lignite
& Peat- Mining
450100 - Military Technology
Weaponry
& National Defense- Chemical Explosions & Explosives
580201 - Geophysics- Seismology & Tectonics- (1980-1989)