PRELIMINARY EXPERIMENTS FOR CRATER MODELING IN CONTROLLED SOIL MEDIA
Interim technical rept.
ARMY ENGINEER RESEARCH AND DEVELOPMENT LABS FORT BELVOIR VA
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The report covers a series of 30-gram, high-explosive cratering tests performed to determine effect soil moisture content in relation to the soils plastic limit has on craters, ground shock velocities, residual displacements, and rarefaction wave. The report concludes a In a cohesive soil the moist condition moisture content within the plastic index as contrasted with the dry condition moisture content well below the plastic limit influences crater formation in the following ways. 1 Fallback into the crater is reduced so that apparent and true crater dimensions are identical. 2 The profile of the crater is more symmetrical and parabolic in shape. 3 The ejecta which consist of large clods, for the most part, are distributed near the crater lip. 4 The crater parameters of depth, diameter, and especially volume are considerably increased. 5 Attenuation rate of the shock velocity is lessened appreciably and results in higher shock velocities and pressures at greater distances from the center of the charge. 6 Larger soil displacements are obtained at any given distance from the center of the charge. 7 The possibility exists that a substantial increase in residual radiation may result from the lack of fallback material. b Large-scale results in marine muck and silty sand compared with results of this study reveal similarity in crater form. This suggests a general hypothesis that any soil which has moisture content that approaches the plastic limit will exhibit similar behavior.
- Soil Mechanics