Effect of Non-plastic Fines on Cyclic Shear Strength of Sand Under an Initial Static Shear Stress

In the present study, a series of undrained cyclic simple shear (CSS) tests were performed on clean Ticino sand (TS) and TS mixed with 10% of nonplastic fines content (FC) under two values of static horizontal shear stress ratio (α = 0 and 0.1) to simulate level ground and sloping ground conditions before earthquake loading, respectively. The results in terms of cyclic resistance were analyzed assuming the global void ratio (e) as control parameter. One of the most significant findings is that the liquefaction resistance of silty sand is lower than that of clean sand due to the presence of fines and this detrimental effect is even more evident in presence of static shear stress. The concept of equivalent granular void ratio (e ∗), proposed earlier to take into account the simultaneous effect of void ratio and fine content based on symmetrical cyclic tests on silty sand, is valid for non-symmetrical tests as well.