Liquefaction Susceptibility of Silty Sands and Low Plastic Clay Soils

Abstract

The present study evaluates the liquefaction susceptibility of non-plastic silty sands and low plastic clay soils at different cyclic stress levels under undrained triaxial loading conditions. Six different types of soil combinations were prepared after blending the silt and clay fractions into the fine sand. Silty sands contain up to 40% non-plastic fines and low plastic clays comprise 10-20% clay fraction. The cylindrical soil specimens were constituted at the medium relative density and isotropically consolidated at 100 kPa pressure. The consolidated specimens were subjected to cyclic stress amplitudes of 0.127, 0.152 and 0.178 using sinusoidal wave loading at a frequency of 1 Hz. Results were presented in terms of pore pressure build-up and axial strain propagation with load cycles, and liquefaction resistance curves. It was found that the non-plastic silty sands and soil mixtures with plasticity indices up to 15 are more susceptible to liquefaction than the fine sands. The criterion on liquefaction susceptibility of low plastic soil mixtures shows that the soil mixtures with plasticity indices up to 15 containing 20% plastic fines exhibit a sand-like behavior and show higher liquefaction susceptibility than fine sands. It is worthy to note that the low plastic soil mixtures with PI ≥ 10 are more resistant to liquefaction than the silty sands (those contain up to 40% non-plastic fines).