CRITICAL UNDRAINED SHEAR STRENGTH OF LOOSE-MEDIUM SAND-SILT MIXTURES UNDER MONOTONIC LOADINGS

Empirical relationships are developed for estimating the undrained critical shear strength
based on experimental triaxial tests under monotonic loadings. The effect of fines content
on the undrained shear strength is analyzed for different combinations of density states.
The parametric study indicates that in terms of the soil void ratio and fines content proper-
ties, the undrained critical shear strength may increase, or decrease as the amount of fines
content increases, consequently showing vulnerability to liquefaction influenced by the fines
content percentage. A series of monotonic undrained triaxial tests have been undertaken on
a reconstituted saturated sand-silt mixtures specimen. Beyond 30% of fines content, it is
shown that a fraction of silt participates in the soil skeleton chain force. In this context,
the concept of the equivalent intergranular void ratio may be an appropriate parameter to
express the critical shear strength of the soil under investigation. This parameter is able
to control the undrained shear strength of non plastic silt and sand mixtures for different
density states.