Detonation of Small Charges Buried in Cohesionless Soil

Abstract

As a preliminary to an experimental program involving larger charges, the detonation of 100 g of the explosive C4 has been analyzed by varying several soil and geometry parameters.

The particle size distribution, mass density and water content of the tested soils have been controlled before and after the shots. Particular emphasis was laid on the influence of the water saturation, and tests were performed on dry and saturated soils. Mass density and water content were measured both by densitometry and by standard laboratory test methods.

The preparation of the soil in the tank, including the protocols of filling the tank with the soil, wetting and compacting steps, has been standardized to improve repeatability. Three depths of burial have been considered. The propagation of the shock wave is visualized via shadowgraphy, which also provides indications on the cone of ejection of the soil particles and ejecta, despite the sand dust.

The speed of propagation of the pressure wave and its time course are recorded through five gauges located on a shaft at the vertical of the charge. The vertical force induced by the explosion is also recorded by a transducer placed at the bottom of the tank. The craters left by the explosion are measured by a 3D scanner.