Postliquefaction behavior of low-plasticity silt at various degrees of reconsolidation

• Various levels of reconsolidation (Ur) were investigated after MRV silt liquefied.
• Postliquefaction shear strength and stiffness steadily increased as Ur increased.
• The critical state lines were different between before and after liquefaction.
• An apparent OCR was induced in postliquefaction reconsolidated conditions.

During earthquake events, low-plasticity silt undergoes a reduction in shear strength and stiffness due to development of excess pore pressure induced by cyclic loading. With reconsolidation, during which process excess pore pressure is dissipated, the shear strength and stiffness can be regained. However, due to the low permeability of silts (compared to sands), the dissipation of excess pore pressure and the reconsolidation of low-plasticity silt takes much more time. This paper investigates the postliquefaction shear behavior of Mississippi River Valley (MRV) silt at various degrees of reconsolidation using triaxial tests. Test results indicate that there was a steady increase, in shear strength and stiffness, at both large and small deformations, with increase in the degree of reconsolidation. The postliquefaction silt showed the effect of the apparent OCR, which had a close effect on postcyclic shear behavior as did the OCR on the static behavior. The critical state lines of MRV silt were different for pre- and post-liquefaction conditions.