THE DYNAMIC RESPONSE OF BURIED CONCRETE ARCHES, PROJECT 3.2 OPERATION SNOWBALL.
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MISS
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The purpose of Project 3.2 was to evaluate the effect of a 500-ton, TNT, surface burst on small, buried, reinforced concrete arch structures. These structures were of such size that they could be tested in laboratory nuclear simulation devices. Nine structures were tested. Three 30-inch-diameter structures with a 4-inch-thick section buried in dry sand to a depth equal to one-fourth the diameter of the arch were located at the 100-, 200-, and 300-psi predicted ground-surface air overpressure levels. Based upon conventional design theory these structures which had tied-independent footings were predicted to fail at overpressures above 200 psi and to move vertically 1 inch. Six semicircular, 12-inch-diameter, unreinforced concrete arch structures with solid base slabs were designed for and placed at the 150-psi predicted ground-surface air overpressure level. Three structures were placed in dry dense sand and three in saturated sand. The three 30-inch structures were subjected to actual air overpressures of 105, 160, and 320 psi and were damaged only slightly. The structure at the greatest range appeared to have suffered greater flexural damage than the closer-in structures. The 12-inch structures were damaged appreciably by ejecta. Generally, the structures responded in a similar manner. In all cases the blast side moved vertically downward, causing an overturning effect. It was concluded that the design techniques used are apparently conservative. Author
- Structural Engineering and Building Technology