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Title: Feasibility of use of simple models to test explosive cratering of roads on slopes in rock
Authors: United States. Assistant Secretary of the Army (R & D)
McAneny, Colin C.
Keywords: Crater models
Explosion effects
Blast effects
Rock blasting
Publisher: Structures Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; SL-79-19.
Description: Miscellaneous Paper
Abstract: Cratering charges were detonated in unstemmed shafts drilled in test beds fabricated of bricks, in order to explore whether such beds might offer a simple approximate way to model the cratering behavior of jointed rock. One-pound TNT charges were fired in four beds on level ground and one on a slope. Scaled depth of burst ranged from 1.1 to 1.7 ft/lb^1/3 (0.44 to 0.67 m/kg^1/3). In two beds where bricks were close-packed but not cemented, rubble mounds rather than apparent craters were formed. The beds appeared to be so permeable that the pressure of the explosion gases was rapidly dissipated and much of the gases' energy was effectively wasted. In cemented beds on level ground, smaller apparent craters resulted than were predicted from published cratering curves for dry rock. In a cemented bed on a hillside, much more damage and material movement occurred than for a comparable bed on level ground. The small apparent craters produced may have. been caused in part by the vertical joints in the beds, which may have induced vertical trajectories of ejecta particles. Excavated true craters in cemented beds were square-shaped with flat floors, conforming to previously published descriptions of true craters in horizontally bedded, vertically jointed rock. The brick beds modeled fresh, unweathered rock with widely spaced joints. No such fresh, massive rock has been present at known field test programs where subsurface charges have been fired and apparent craters studied. Also, in being unstemmed, the brick shots differed from most reported cratering tests. The brick cratering results appear to compare realistically with nature, in view of the test conditions. Therefore, the technique should be useful for studying cratering behavior in jointed rock in various topographic configurations, where approximate answers are acceptable.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Miscellaneous Paper

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