"Both detonation pressure and borehole pressure, resulting from an explosion within blastholes in rock, perform specific functions in the fragmentation of the rock and the generation of ground vibrations. The results of previous investigations would suggest that control of these pressures in the borehole would, to some extent, control the size distribution of the blasted particles. One method of influencing detonation and borehole pressures is by varying the hole diameter in relation to a constant charge diameter, called decoupling, and by varying the medium between the explosive charge and the rock.
This investigation examined the effects of geometric coupling, which is the ratio of the charge diameter to the hole diameter, using water and air coupling mediums, on the degree of fragmentation. A total of eleven reduced-scale in situ bench blasts were performed, and the broken rock resulting from each blast was screened into eight size—fractions. These size-fractions were grouped into coarse, medium, and fine size ranges in accordance with a scaling factor ranging between 10 and 15.
The results indicated that a linear relationship exists between geometric coupling and the corresponding cumulative weight percentages in each size range for both air and water coupling. Percentages of material in all size ranges, particularly the coarse and medium, can be controlled to some extent by geometric coupling ratios and the coupling medium. In general, water coupling produced greater degrees of fragmentation and lower magnitudes of peak particle velocity than did air coupling"--Abstract, page ii.
Haas, Charles J.
Aughenbaugh, N. B.
M.S. in Mining Engineering
University of Missouri--Rolla
xi, 108 pages
© 1983 Timothy Wayne Warden, All rights reserved.
Thesis - Open Access
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Warden, Timothy Wayne, "Control of rock fragmentation through explosive coupling" (1983). Masters Theses. 4038.