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The objective of this project was to study some of the factors affecting the transmission of air-blast-induced pressure through soil and the loading produced on buried structures by such pressures in the high-pressure region (approximately 250 psi). Factors studied were: (1) the attenuation of pressure in a sand deposit when the water table is a few feet below the ground surface; (2) the effect of duration of positive phase of blast on the pressure transmitted through such a soil; (3) the effect of structure flexibility on the pressure acting on structures buried in such a soil; and (4) the relationship between horizontal and vertical pressures in such a soil. The project employed 43 devices, each a rigid cylinder having one rigid end and one deformable-diaphragm end. The devices were buried at depths ranging from 0 to 20 feet at each of two locations at the Eniwetok Proving Ground. The locations were chosen to give a predicted ground surface overpressure of about 250 psi from each of two shots, Cactus and Koa. keywords: NTPR(Nuclear Test personnel Review)., Extracted version of report dated 3 May 61.

The primary objective of the project was to obtain information regarding the effect of the length of the positive phase of blast on the response of drag and semidrag structures. A total of six steel-frame buildings were tested during this operation. The structure of each type nearest ground zero was located such that if the yield of the weapon was near the lower limit of its predicted range, it would probably undergo considerable inelastic deformation. Conversely, those structures farthest from ground zero were located such that if the yield of the nuclear device was near the upper limit of its predicted range, they would be substantially deformed, but would not collapse. The third building of each type was located at an intermediate point between these two extremes. Instrumentation was provided to obtain records of the transient structural deflections, strains, and accelerations, as well as of overpressure and dynamic pressure versus time at the sites of the various test structures., Extracted version of report dated 5 Aug 59.

The behavior of soil under dynamic loading is an important factor in the soil-structure interaction problem. To study this behavior, a series of dynamic, high-pressure triaxial and one-dimensional compression tests has been conducted. Special testing devices developed for this research are described. In the one-dimensional tests, the peak pressures ranged from 620 psi to 11,300 psi with rise times to the peak pressure of 1.9 milliseconds to 1,625 milliseconds. In the triaxial tests, cell pressure from 100 psi to 1,010 psi were used with times-to-failure varying from 3 milliseconds to 100 seconds. In addition, partial loading triaxial tests were run in which the applied axial stress was 20 percent to 60 percent of the failure stress. The soil used was a compacted silty clay of low plasticity. The test results are presented and the influence of rate of loading and pressure level on compressive strength, ratio of lateral to axial pressures, stress-strain relations, residual strains, and creep under constant load are evaluated.

The objective was to study some of the factors affecting the transmission of air-blast-induced pressure through soil and the loading produced on buried structures by such pressures in the high-pressure region (approximately 250 psi). Factors studied by this project were: (1) the attenuation of pressure in a sand deposit when the water table is a few feet below the ground surface; (2) the effect of duration of positive phase of blast on the pressure transmitted through such a soil; (3) the effect of structure flexibility on the pressure acting on structures buried in such a soil; and (4) the relationship between horizontal and vertical pressures in such a soil. (Author), Report on Operation Hardtack--Project 1 9.

Two buried reinforced concrete four-walled structures without floor or roof were tested, one at 200 feet and the other at 250 feet from a 1.2 kt device buried at a depth of 67 feet. The structures were instrumented to give transient load and response data. In addition, provisions were made to obtain data on permanent displacements and strains. The crater formed by the explosion was unexpectedly small, being 146 feet in radius, so that the two targets were approximately 50 and 100 feet from the edge of the crater. The structures responded primarily as rigid bodies and followed the soil motion; consequently there was no structural damage. The permanent movements of the boxes were 3.8 feet and 0.5 foot, horizontally, away from the point of burst. It is concluded that buried structures of the type tested are difficult to damage structurally, unless located within or close to the edge of the crater and that, for structures outside of the crater, problems created by large earth movements and throwout might be critical for structures relatively close to the edge of the crater., Rept. on Operation TEAPOT, Nevada Test Site, Feb-May 55. Declassified 11 Aug 61.

The report describes the results of a test to determine the nature of forces transmitted through earth to buried structures from the explosion in air of an atomic bomb. The structures were primarily reinforced concrete boxes having a large number of simply supported steel beam strips forming their roofs. Three structures were included in the program, having respectively 1 ft, 4 ft, and ft of earth cover over the beam strips, and each of the structures had a number of individual beam strips, with several strips of each of three different degrees of flexibility to provide information concerning the effect of flexibility of the structure on the loading transmitted to it. All of the beam strips had the same span, namely 8 ft. The structures were tested in two shots, the first producint an overpressure level of about 15 psi, and the second about 63 psi., Rept. on Operation Upshot-Knothole, Nevada Proving Grounds, Mar-Jun-53, Project 3.8.

The objectives of this project were two fold. First, it was intended to obtain experimental evidence in support of the theoretical concept that the peak intensity of overpressure necessary to produce a given deflection of a drag or semidrag structure decreases as the duration of the positive phase of the blast wave increases. The second objective was the evaluation of present methods of predicting the response of drag and semidrag structures under relatively low intensity blast pressures and the utilization of the results of this project to refine and improve these methods., Rept. on Operation Teapot, Nevada Test Site, Feb-May 55. Prepared in cooperation with Illinois Univ., Urbana.

The general purpose of this project was to obtain the necessary basic data from which to develop criteria for the economical and efficient design of underground protection from air-blast forces. The specific objectives were: (1) to investigate the nature of the forces transmitted from an air burst of an atomic device through the earth to underground structures; (2) to determine the variation of these forces with the depth of the structure in the earth and with the flexibility of the structural elements; and (3) to study the response of simple structural elements of different stiffnesses and effective masses subjected to the transmitted dynamic forces., Rept. on Operation Teapot, Nevada Test Site, Feb-May 55.