Reexamination of effect of plasticity on liquefaction resistance of low-plasticity fine-grained soils and its potential application

The paper summarizes a compilation of existing cyclic experimental data on reconstituted and undisturbed specimens of low-plasticity fine-grained soils to assess liquefaction resistance. The authors normalized the data to reduce the effect of other relevant factors such as shear mode, density, effective confining stress and cyclic loading frequency. It is indicated that liquefaction resistance of the specimens reconstituted using slurry consolidation approach is lower than that of the undisturbed specimens. The liquefaction resistance for undisturbed specimens decreases with an increase in the plasticity index up to 4–5 and then increases with a further increase in plasticity index. A new correction factor K _PI to estimate the effect of plasticity index on cyclic resistance ratio is proposed for design purposes and added into the framework of liquefaction evaluation of claylike fine-grained soils with PI of 7–18 (change to 5–18, if ML–CL) on the base of the approach of Boulanger and Idriss. Because the effect of plasticity index on liquefaction resistance is slight when the plasticity index is <7, it is suggested that the liquefaction evaluation of sandlike fine-grained soils with PI of 0–7 (changed to 0–5, if ML–CL) follows the framework of simplified procedures using SPT and CPT data.