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Abstract Low-plasticity silt widely spreads all over the world， and its liquefaction easily develops in earthquake events. Some failure of civil infrastructures happened not only during but also after earthquakes，indicating that it is necessary to study postcyclic behavior of low-plasticity silt. The Mississippi River Valley silt in central America was selected as testing material. Excess pore water pressure was produced by cyclic loading in cyclic triaxial testing system and then dissipated for reconsolidation. Monotonic and cyclic triaxial tests were respectively conducted on two series of specimens experiencing the previous dynamic shearing. The testing results show that the dynamic shearing with a liquefaction level larger than 0.70 produced significant increases in the volumetric strain due to reconsolidation and undrained shear strength. Compared to sand，the Mississippi River Valley silt has an obvious increase on undrained shear strength at lower liquefaction level. The previous dynamic shearing showed a different effect on liquefaction resistance with on undrained shear strength. With a liquefaction level of 0.35 or a cyclic axial strain of 0.2%，the liquefaction resistance reached the peak and then decreased with an increase in liquefaction level larger than 0.35. With a large compression strain due to previous dynamic loading，the excess pore pressure developed less in the compression than in the extension during the second cyclic loading after reconsolidation.
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Received: 28 June 2012
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2013, Vol. 32 
