Behavior of Stiff Cylinders Buried in Sand Under Static Loading

The objective of this investigation was to study experimentally the elastic behavior of horizontally oriented, stiff cylinders buried at shallow depths in dense, dry sand and subjected to static surface overpressures. Static tests were conducted on nine different cylinders in the U.S. Army Engineer Waterways Experiment Station's Small (4-foot-diameter) Blast Load Generator (SBLG). The cylinders were fabricated from steel mechanical tubing having a 6- inch outside diameter and a specially isolated 12-inch-long test section. The nine test specimens comprised three groups of cylinders with wall thicknesses of 1/8, 1/4, and 3/8 inch that corresponded to stiffnesses (EI/R3) of 170, 1,644, and 5,926 psi, respectively. In order to study the effects of burial depth, the first, second, and third cylinders of each group were tested at depths of 3, 6, and 9 inches, respectively. A total of 14 static tests were conducted, 9 on virgin soil samples and 5 on samples that had been previously loaded. The peak surface overpressure attained for all tests was approximately 1,000 psi. Measurements were made of cylinder hoop strain, vertical diameter change, soil stress, and surface overpressure.