Stress Wave Propagation in Unsaturated Sands. Volume 1. Centrifuge Modeling

摘要

Explosive model testing was conducted using a geotechnical centrifuge in order tosimulate prototype stresses and ground motions in a representative cohesionless backfill. Models were constructed of sand and compacted moist to a constant void ratio using a vibratory technique. Exploding detonators were used to simulate contained bombs in the backfill material. The objective of this study was to determine the influence of moisture content, at the time of backfill compaction, on blast induced stress wave propagation. Models were constructed to 1/18.9 and 1/26.3 scales. Explosives consisted of 1031 mg and 350 mg of PBX 9407 and were buried to depths of 7.6 cm and 5.4 cm respectively. These scaled models simulated prototype charges of 6.9 kg and 6.4 kg (7.8 kg and 7.3 kg TNT equivalent) at a depth of burial of 1.4 meters. Attenuation coefficients (n) show some influence with respect to saturation. Peak stress and peak particle acceleration intercepts at a scaled distance of one are lowest at 0 and 53 percent saturations and are maximum at 35 percent saturation. Peak particle velocity intercepts are lowest at 0 and 70 percent saturations and again are maximum at 35 percent saturation.