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|Title:||Decoupling of ground shock from explosions in rock cavities|
|Authors:||United States. Army. Office of the Chief of Engineers.|
Drake, James L.
|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-74-1.|
Abstract: Decoupling explosive energy by detonating charges in cavities larger than the charge is an effective method for reducing ground shock magnitudes over those of' fully contained bursts. The blasting industry deliberately decouples explosives in presplitting, smooth wall, and cushion blasting operations. This method has been explored as a possible method for concealment of underground nuclear explosions. Decoupling can be an effective means of significantly reducing the energy coupled into the earth by accidental explosion of magazines. This paper presents an analysis of ground motions generated by decoupled explosions in rock cavities. A simplified elastic solution is used to calculate particle motion magnitudes and time histories produced by an explosion in rock as a function of the initial cavity radius and the loading density of the explosive. Loading density is defined as the total explosive weight divided by the initial cavity volume. Initial cavity conditions were estimated from the adiabatic expansion of the explosive products as an ideal gas for slightly decoupled conditions, and empirical data were used to extrapolate initial cavity conditions to low loading densities experiments in three explosive charges particle velocity or the initial cavity. Results compare favorably with data obtained from decoupling different rock types where sources ranged from small high to low-yield nuclear explosions. Spatial attenuation of peak strain and positive duration of particle motion are dependent size and magnitude of motion on the loading density.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Miscellaneous Paper|
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