The Influence of Fines Content on the Onset of Instability and Critical State Line of Silty Sand

Abstract

This communication presents the results of an experimental study in the laboratory on the mechanical behavior of silty sand through conventional compression triaxial tests, under both drained and undrained conditions. We particularly put an emphasis on the effect of fines content on the evolution of the maximum and the minimum void ratio, the onset of instability and the critical state line. Several series of monotonic triaxial tests were carried out on sand/silt mixtures, with fines content ranging from 0 to 20 %. In some series, the samples were reconstituted at the same initial global void ratio e_i while in other ones, the samples were reconstituted at the same initial intergranular void ratio ${{\text{e}}_{\text{i}}}^{\text{g}}$ to simulate the mechanical behaviour of natural material subjected to erosion phenomenon such suffusion where the fines are removed and the sand matrix kept constant. The results from this study revealed that the fines content affects both the liquefaction potential of silty sand and the position of the critical state line. Moreover, the results showed that the effect of fines depends strongly on the density parameter used for the interpretation, void ratio or intergranular void ratio.