Limit void ratios and steady-state line of non-plastic soils

Abstract

The significant amount of laboratory testing required to determine the steady-state line (SSL) of soils has led to an interest in understanding how the SSL correlates with simpler soil index properties. Correlations proposed so far for non-plastic soils are only applicable to sands with fines content (FC) up to about 35%, but many geotechnical applications involve higher FC values. This work explores FC-independent correlations between the SSL and the limit void ratios by adopting the familiar straight line idealisation of the SSL projection on e–log(p′) space. Two parameters, Γn and λ, are used to represent the vertical location and the slope of the SSL, respectively. Using a database of 149 non-plastic soils, it is shown that there is a functional correlation between Γn and the minimum void ratio (emin) that is independent of particle size distribution, including FC, and particle angularity. A weak λ–emin correlation is also observed which can provide some guidance with respect to compressibility. Although the accuracy of the correlations is insufficient to make reliable quantitative SSL estimations, they are useful in guiding the selection process of samples whose SSLs have to be formally determined in order to characterise the SSL variability of non-plastic soil deposits.