关键词: 低塑性粉土, 液化, 重固结, 不排水剪切强度

Abstract: The postliquefaction undrained shear strength of low-plasticity silt from Mississippi River Valley in Central America was studied after the silt experienced reconsolidation. It is found that postliquefaction undrained shear strength of the normally consolidated silt increases with an increase in reconsolidation level; and apparent overconsolidation phenomenon is shown in the silt. Similar to the silt without previous cyclic loading, normalized ratio of undrained shear strength for postliquefaction specimens Su,OC/Su, NC with complete reconsolidation has a power function with overconsolidation ratio OCR; but the power exponent for postliquefaction silt is a little higher than that for the silt without previous cyclic loading. With an increase in OCR, the reconsolidation induced change of undrained shear strength ?Su, recon increases first and then decreases; and then it reaches the peak when the OCR is 3.42. The postliquefaction silt with reconsolidation does not have quasi-steady state during undrained shearing; and deviator stress keeps increasing with an increase in axial strain until the silt reached critical state. In addition, the stress-strain curves of postliquefaction silt with complete reconsolidation can be normalized by effective consolidation pressure ? ′c. Finally, an equation is proposed to calculate undrained shear strength of postliquefaction low-plasticity silt with complete reconsolidation.

Key words: low-plasticity silt, liquefaction, reconsolidation, undrained shear strength