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Title: Operation MINE SHAFT : distribution of natural and artificial ejecta resulting from detonation of 100-ton TNT charge on granite, MINERAL ROCK Event
Authors: United States. Defense Nuclear Agency.
Meyer, John W.
Rooke, Allen D.
Keywords: Crater ejecta
Explosion effects
Mine Shaft (Series)
Mineral rock (Event)
Publisher: Weapons Effects Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; N-73-4.
Description: Miscellaneous paper
Abstract: Event Mineral Rock, the detonation of a 100-ton spherically shaped charge of TNT on granite, was the last event of the Mine Shaft Series, a program of high-explosive tests primarily concerned with ground shock and cratering effects from explosions at or near the surface of a competent rock medium. The series, conducted in 1968 and 1969, was intended as a follow-on to previously conducted similar experiments in soil. Mineral Rock (1969) duplicated the geometry and yield of Event Mine Ore (1968). Studies of crater ejecta were conducted to determine debris density and distribution, to examine the role of the ejection mechanism in crater formation, and to obtain additional information on the hazards associated with natural missiles. Mineral Rock, with a maximum observed ejecta range of approximately 2,800 feet for a 1-pound particle, produced a larger crater and a more extensive ejecta field than its predecessor, Mine Ore. In addition to established methods of ejecta measurement, aerial photography was introduced to obtain spoil volume and distribution parameters. A comprehensive artificial missile experiment was included, and limited impact measurements were obtained from the terminal trajectories of small natural particles. As with other events in rock that preceded the Mine Shaft Series, the influence of rock jointing on ejecta distribution was evident. Volumetric analysis indicated that 230 yd3 of in situ material was ejected from the crater, about 90 yd3 of which was deposited in the crater lip. A factor of W 0.3 (W = charge weight) was confirmed for empirical scaling of ejecta ranges common to the Mine Ore/Mineral Rock test geometry. Size distribution as a function of range for discrete particles was also established, confirming that smaller particles (4 to 8 inches in diameter) tend to dominate the ejecta field at distances greater than 25 to 30 crater radii from the detonation. Throwout regions common to the Mine Ore/Mineral Rock test geometry were satisfactorily defined, with good agreement being noted between the two events. In general, the ejecta mechanics resembled those associated with a surface burst in soil.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Miscellaneous Paper

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