MINE SHAFT Series, Events MINE UNDER and MINE ORE : ejecta studies
Meyer, John W.; Rooke, Allen D.
Miscellaneous paperAbstract: The MINE SHAFT Series is a program of high-explosive tests primarily concerned with ground-shock and cratering effects from explosions at or near the surface of a rock medium. The series is sponsored by the Defense Atomic Support Agency (DASA) as a follow-on to similar tests in soil (SNOW BALL, DISTANT PLAIN, PRAIRIE FLAT). The two major events of MINE SHAFT during 1968 were MINE UNDER and MINE ORE; both were explosions of 100-ton TNT spheres detonated in nearsurface geometries and in/over a granite medium. Studies of the crater ejecta were conducted on MINE ORE (buried one-tenth of the charge radius) with the objectives of determining the spoil density and distribution from this event, examining the role of the ejection mechanism in crater formation for this medium, and obtaining additional information on natural missile trajectories. MINE UNDER, an above-surface event, produced a spalled rubble mound and a small field of debris; this was also recorded as part of the study. MINE ORE produced a low, irregular crater lip which extended to an average range of 47 feet from ground zero (GZ) with a maximum of roughly 90 feet. Beyond this, discrete ejecta particle size and distribution frequency decreased with increasing distance from GZ. The maximum observed range was 2,120 feet for a 1-pound natural missile with smaller fragments found out to about 2,300 feet from GZ. Maximum ejecta ranges were observed downhill from and parallel to the main joints. Missile ranges scaled approximately as w 0.3. The jointing system of the rock appeared to be the single most influential element in concentrating debris along certain radials, as well as in the overall distribution of debris.
Weapons Effects Laboratory (U.S.)Engineer Research and Development Center (U.S.)
Cratering; Crater ejecta; Ejection; Explosions; Ground shock; Mine Ore (Event); Mine Shaft (Series); Mine Under (Event)
Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; N-69-2.
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