Effect of gradation and fines content on the undrained response of sand

A systematic study of the effect of grain size, gradation and silt content on the monotonic and cyclic undrained loading response of sand is presented. The objective is to gain an improved understanding of the behavior of fluvial and hydraulic fill sands. Loose silty sands are shown to possess similar cyclic strengths regardless of silt content, even though they have widely different void ratios. The concept of sand skeleton void ratio is introduced in order to explain the observed behavior of silty sands with varying fines content. Improved gradation tends to make clean loose sands more dilatent in compression and less contractive in extension.