Abstract: The aim of this study is to explore the influence of sand content on strength characteristics of sand-silt mixtures. To this end, triaxial consolidated drained shear tests and MIP tests were conducted on sand-silt mixtures with varied sand content. Test results indicate that as sand content increases, both the internal friction angle and peak deviatoric stress of sand-silt mixture increase while cohesion decreases. Such changes were more pronounced when sand content is below 30%, and then weakens and tends to stabilize. The increment of peak deviatoric stress raises as the confining pressure increases. When sand content is less than 15%, the strength of sand-silt mixture is controlled by cohesive strength. As sand content increases, the role of frictional strength gradually surpasses that of cohesive strength in influencing the overall strength. The volume shrinkage of the sand-silt mixture leads to a denser soil structure, resulting in an increase in the internal friction angle and peak deviatoric stress.

Key words: sand-silt mixture, sand content, peak deviatoric stress, MIP test, micro-mechanism, strength property