Abstract
The determination of shear wave velocity (Vs) in soil and the associated small-strain shear modulus (G0) plays an important role in many geotechnical applications. In the last decades extensive laboratory experiments have been carried out to study these two properties for clean quartz sands. Often natural sands are not clean but contain some amount of fines (referred to as silty sand in practice). The effect of fines on the shear wave velocity and shear modulus is therefore a matter of concern. This paper presents an experimental study on mixtures of clean quartz sand and crushed silica fines at different percentages of fines. A series of resonant column (RC) and bender element (BE) tests were carried out for a range of confining stresses and void ratios. It is found that G0 values obtained from the BE tests are significantly greater than the ones obtained from the RC tests, indicating the importance of testing method for silty sand. For either method, however, the G0 value of the mixture always decreases with an increase of fines content. An empirical model is proposed for estimating G0 which allows for both the effect of fines and the stress and density dependence, and it is shown to possess a reasonably good performance.
