Elastic response of shock-isolated cylinders buried in a dense, dry sand
Foster, David C.
Technical reportAbstract: The objective of the study was to investigate the elastic response of a stiff, horizontally oriented, steel cylinder backpacked with a low-strength cellular concrete and buried in a dense, dry sand, whose surface was subjected to static and dynamic overpressures. Four series of tests were conducted on the cylinder (one static and one dynamic series without backpacking, and two dynamic series with backpacking). The cylinder had an outside diameter of 6 inches, a 0.120-inch wall thickness, and a stiffness of 164 psi. Static and dynamic surface overpressures ranged from 0 to 250 psi and from 100 to 250 psi, respectively. In the tests with backpacking, a layer of cellular concrete with a thickness of either 1-3/8 or 2-7/8 inches encompassed the cylinder. The average compressive yield strengths of the cellular concrete were 40 and 26 psi. The cylinder was buried at a depth of 15 inches, which was held constant for all tests. Measurements were made of the strains and accelerations experienced by the cylinder, test chamber bonnet pressure, surface overpressure, and free-field pressure and acceleration. Backpacking reduced the peak strains experienced by the cylinder, and a redistribution of the strains in the cylinder occurred. The strain values were reduced by approximately 20 and 40 percent, respectively, for the 1-3/8- and 2-7/8- inch-thick layers of backpacking that were utilized. Bending moments and thrusts indicated that a 1-3/8-inch-thick layer of backpacking did not significantly affect the response of the cylinder. A 2-7 18-inch-thick layer of backpacking reduced the moments and thrusts to magnitudes generally less than 50 percent of those for the cylinder without backpacking. For all tests utilizing backpacking, the accelerations of the cylinder were reduced to approximately 10 to 50 percent of those measured in corresponding tests without backpacking.
Weapons Effects Laboratory (U.S.)Engineer Research and Development Center (U.S.)
Backpacking; Buried cylinders; Cellular concrete; Cylinders; Dynamic loads; Static loads; Elastic properties; Sands
Technical report (U.S. Army Engineer Waterways Experiment Station) ; N-69-6.
Approved for public release; distribution is unlimited.