Small-strain shear modulus of silty sands: the role of sample preparation method

Abstract

Establishing the influence of sample preparation method on shear wave velocity or associated small-strain shear modulus (G0) of silty sands is a subject of considerable interest. This paper presents an attempt to address this topic through a comprehensive experimental programme covering four sample preparation methods. The experiments were conducted on clean Toyoura sand and its mixtures with two types of fines of different sizes. For each sample preparation method, a range of void ratio and confining stress was investigated to obtain a comprehensive view of the influence of sample preparation and its interplay with other factors. One of the notable findings is that, compared with clean sand, the difference of G0 induced by different sample reconstitution methods can be much enlarged for silty sand, and the influence is coupled with the size disparity ratio of the mixtures. The reduction of G0 due to the presence of fines also depends on sample preparation method and for smaller fines the reduction is more significant. A careful examination of the X-ray images of the specimens made by different methods suggests that the observed effects are mainly associated with the different contact conditions of coarse and fine grains.