Spherical Waves in Saturated Sand.

Abstract

Abstract : The Naval Surface Warfare Center needs to develop the capability to determine numerically the characteristics of a propagating stress wave in saturated sand. To provide needed experimental data, SRI International performed precision experiments with the objective of measuring saturated sand material response resulting from the detonation of a spherical explosive charge. The instrumentation consisted of particle velocity gages as the primary measurement tool and stress gages as a secondary measurement tool. Four experiments were performed using Eglin Beach sand at nominal saturation levels of 100%, 95%, and 78%, and 77%. The particle velocity time histories of the 100% and 78% saturated sand models showed 20% higher peak particle velocities in the 78% saturated sand model at ranges up to 2.04 cm from the charge and 30% lower peak particle velocities in the 78% saturated sand model at ranges beyond 3.05 cm from the charge. The higher peak particle velocity in the 78% saturated sand model near the charge is due to the lower inertial resistance because of less water in the pore space. The lower peak particle velocity in the 78% saturated sand model farther away from the charge is the result of larger attenuation of the particle velocity.