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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 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. 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. (Author).
The general objective of the investigation was to study experimentally the behavior to failure of flexible, horizontally oriented cylinders buried at various depths in dense, dry sand and subjected to either static or dynamic surface overpressures. Static and dynamic tests were conducted on 33 different cylinders, fabricated of high-yield-strength aluminum. Results indicated that collapse of the cylinders occurred while the strains in the cylinder walls were still in the elastic range. The cylinders buried at the shallow depths (zero to one-half cylinder diameter above the crown) collapsed by a catastrophic snap-through or caving of the crown. For the cylinders buried at depths of three-quarters to two cylinder diameters above the crown, the mode of collapse was an instantaneous elastic buckle that occurred at the spring line or invert of the cylinder. The collapse mode of the cylinders under dynamic overpressure was similar to that of the cylinders collapsing under static overpressure. The results of the investigation verified the applicability of an equation for predicting the static collapse overpressure for smooth-walled, horizontally oriented, buried cylindrical structures and entranceways. The hoop-compression theory was found to be applicable for analyzing the structural design to determine if the cylinder would collapse in the elastic range. (Author).
Much of the infrastructure of modern society is buried below ground. Pipeline, conduits and culverts carry the services on which our economies depend and the strength and resilience of such structures is of vital importance. Larger underground construction is becoming more common in cities and towns, and in defence installations. This book brings t
This report contains summaries of all research reports dealing with nuclear weapons effects on hardened structures, published under Project 1080 by the AFWL Structures Branch (formerly the AFSWC Structures Division) and predecessor organizations from July 1951 to February 1964. Section I contains edited abstracts of unnumbered reports, technical memoranda, technical notes, technical reports, and technical documentary reports. Section II lists all reports by document number (unnumbered reports are listed chronologically); Section III lists reports by subject area; and Section IV lists reports by contractor.