Elastic Wave Velocities in Granular Soils

Laboratory tests, using the resonant column method, were conducted to evaluate the longitudinal and shear wave velocities in specimens of Ottawa sand, crushed quartz sand, and crushed quartz silt. The variables considered were the confining pressure, and the moisture content, void ratio, and grain characteristics of the materials. The wave velocities for the sands varied with approximately the 1/4 power of the confining pressure. At a given confining pressure, the velocity varied almost linearly with void ratio. A diagram is included that shows these relationships over a range of void ratio from 0.3 to 1.3 and confining pressures between 500 psf and 6,000 psf. The effects of relative density, grain size, and gradation entered only through their effects on void ratio. The wave velocities in the quartz silts were found to be greatly dependent on time.