Liquefaction of Unsaturated Sands

Abstract

Recent laboratory tests and field observations have revealed that unsaturated sands are susceptible to liquefaction. Systematic investigation of liquefaction potential of unsaturated sands is, however, lacking. In this paper, a coupled hydromechanical elastoplastic constitutive model for unsaturated sands is calibrated using available laboratory test results. A parametric study is then conducted using the calibrated constitutive model to investigate the effects of initial degree of saturation, relative density, and effective confining pressure on the liquefaction resistance of unsaturated sands. The results suggest that the liquefaction resistance of unsaturated sands increases with decreasing degree of saturation and increasing relative density and effective confining pressure. The results also reveal that the effect of degree of saturation on liquefaction resistance is more pronounced near 100% degree of saturation. The results of the parametric study are then condensed to create a design chart that can be used for liquefaction potential evaluation of unsaturated sands. The degree of saturation, relative density, and effective confining pressure are taken into account in this design chart.