Abstract: In order to investigate the impacts of fine content FC, relative density Dr and initial effective confining pressure on the shear wave velocity Vs of sand-silt mixtures, a series of bender element tests was performed on saturated sand-silt mixtures with different FC, Dr and . The test results show that Vs of loose and medium-dense mixtures firstly decreases and then increases as FC increases, while Vs of dense mixtures presents a trend of decreasing. At a fixed FC, the Vs of the mixtures decreases monotonically with the increase of the consoildated void ratio ec, but there is no a single negative linear relationship between Vs and ec of different FC mixtures. It is found that the Vs of mixtures with different FC, Dr and decreases monotonically with the increase of the equivalent skeleton void ratio esk*. The test data of three types of sand-silt mixtures in the literature also support this conclusion. The test results show that esk* is the only physical state index with negative linear correlation with Vs of sand-silt mixtures.

Key words: sand-silt mixtures, shear wave velocity, fines content, equivalent skeleton void ratio