In order to investigate the impacts of fine content FC

relative density D

r

and initial effective confining pressure ■ on the shear wave velocity V

s

of sand-silt mixtures

a series of bender element tests was performed on saturated sand-silt mixtures with different FC

D

r

and■. The test results show that V

s

of loose and medium-dense mixtures firstly decreases and then increases as FC increases

while V

s

of dense mixtures presents a trend of decreasing. At a fixed FC

the V

s

of the mixtures decreases monotonically with the increase of the consoildated void ratio e

c

but there is no a single negative linear relationship between V

s

and ec of different FC mixtures. It is found that the V

s

of mixtures with different FC

D

r

and ■ decreases monotonically with the increase of the equivalent skeleton void ratio e

sk

*. The test data of three types of sand-silt mixtures in the literature also support this conclusion. The test results show that e

sk

* is the only physical state index with negative linear correlation with V

s

of sand-silt mixtures.