Centrifuge Modeling of Projectile Penetration in Granular Soils.

摘要

Investigations of the projectile penetration phenomenon in granular soils have been impeded by the difficulty in adequately quantifying and characterizing soil targets, and by the inability to directly scale results of 1-g penetration tests to full-scale conditions. The former is largely due to the failure to adequately prepare and quantify laboratory test samples, and the inherent limitations involved with testing and quantifying in situ soils. The latter is associated with an incomplete understanding of the soil parameters involved in the projectile penetration event. A series of laboratory tests on dry sands was conducted to assess the influence of confining pressure on projectile penetration depth, using a centrifuge to simulate full-scale stress levels in the soil targets. Projectiles were fired from a Thompson Contender pistol at impact velocities of approximately 305 meters/second into the rotating soil samples. Corresponding tests were conducted under 1-g conditions. A limited number of centrifuge and 1-g tests were conducted on moist samples. Most tests involved vertical impact angles; a few tests were conducted at other than normal impact angles to illustrate the flexibility of the firing system design. The targets were prepared using a pluviation technique that resulted in uniform, reproducible samples of known density; this sample preparation technique contributed to the reproducibility of penetration test results that was observed in the test program. Significant differences in projectile penetration depths were obtained for different soils and for the same soils prepared at different densities. (sdw)