Evaluation of Wave Dissipation in Sand under Impact Loading

Abstract

When the ground is subject to dynamic compaction such as aircraft wheel loading and pile driving, the wave dissipates in soil, which has not been fully understood qualitatively and quantitatively. This paper reports a series of split-Hopkinson pressure bar (SHPB) tests on silica and calcareous sands with various length-to-diameter ratios, initial void ratios, and degrees of saturation. A dimensionless parameter, the modified attenuation coefficient, is introduced to quantify the wave dissipation in sand. It is found that the modified attenuation coefficient of dry sand increases linearly with the initial void ratio. The modified attenuation coefficient of unsaturated sand first increases with the degree of saturation and then decreases. The peak attenuation coefficient corresponds to the largest capacity of wave dissipation and the smallest loaded area. Based on experimental data, semiempirical predictive equations are obtained. The capacity of wave dissipation in the studied sand with various initial void ratios and moisture contents can be predicted preliminarily by four SHPB tests and the semiempirical equations.