EFFECTS OF FINES ON MONOTONIC UNDRAINED SHEAR STRENGTH OF SANDY SOILS

The seismic stability of slopes is governed by the shear strength of liquefied sands. This paper presents experimental data on a host sand mixed with different amounts of fines content. A careful analysis of other available steady state strength (S sub us) data, combined with the experimental data, show that fines content and relative density play important roles affecting S sub us. Fines content is found to be the major factor affecting S sub us. The S sub us data for sands are grouped into three groups, namely, relatively clean sands ( 50% fines). It is found that at the same relative density, relatively clean sands show the highest S sub us. Silts show the lowest S sub us. Silty sands show intermediate strengths. Based on this data, lower-bound relationships are proposed for S sub us as a function of relative density (D sub r) and fines content.