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Title: Earth motion and stress measurements. Project LN302, Operation Dial Pack
Authors: United States. Defense Nuclear Agency.
Murrell, Donald W.
Keywords: Dial pack (event)
Earth movements
Explosion effects
Ground motion
Ground shock
Shock waves
Soil stresses
Publisher: Weapons Effects Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical report (U.S. Army Engineer Waterways Experiment Station) ; N-74-3.
Abstract: Abstract: The objectives of this study were to measure and to analyze the earth motions and stresses produced by the Dial Pack 500-ton TNT detonation. Particle acceleration, particle velocity, and soil stress gages were installed to measure the ground motions and stresses in the 1,500- to 50-psi predicted airblast overpressure region (83 to 540 feet from ground zero) at depths below the ground surface of 1.5 to 30 feet. Time histories of all successful measurements are included in Appendixes A and B. Ground shock arrival time data indicated the occurrence of outrunning ground motion at the ground surface at a distance of about 600 feet from ground zero, or the 35-psi pressure level. Peak vertical particle accelerations varied from 1,400 g's near ground zero to 8 g's at the extremes of the instrumented region, attenuating sharply with both distance and depth. An equation was developed to describe the peak acceleration as a function of both pressure and depth. Downward vertical particle velocities varied from 72 to 0.88 ft/sec over the area instrumented, also attenuating rapidly with distance and depth. An equation similar to that for acceleration was developed to express velocity as a function of pressure and depth. The downward velocity pulse was followed by an upward motion of generally longer duration and, except at the lesser ranges and 5- and 10-foot depths, lesser magnitude. Peak horizontal particle velocities varied from about 20 to 0.35 ft/sec over the range instrumented, attenuating as the -2.1 power of distance. They did not vary with depth. Both horizontal and vertical displacements were calculated from measured velocities. Maximum transient displacements were 20 feet upward and 20 feet outward at the 83-foot range and 1.5-foot depth. The upward displacement attenuated more rapidly than the outward displacement with distance, so that at 540 feet it was only about one-half of the outward displacement.
Description: Technical report
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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