Effect of silt uniformity on the liquefaction resistance of sand-silt mixtures

Literature review revealed that effects of particle segregation and silt uniformity on the liquefaction resistance of sand-silt mixtures are not well understood. Therefore, cyclic direct simple shear tests were conducted to investigate effects of silt uniformity and stratified structures on the liquefaction resistance of sand-silt mixtures with 0%-40% fines content (FC). FC ). For all uniform sand-silt mixtures, as FC increased up to 20%, liquefaction resistance decreased, while it increased as FC increased from 20% to 40%. The liquefaction resistance of the samples with uniform silt only in the top and bottom layers was slightly higher than that of a uniform sample (USM), USM ), while the cyclic strength of the samples with silt concentrated in the middle layer was greater (up to 23%) than that of other nonuniform samples. USM exhibited the least liquefaction resistance. In addition, the number of silt layers ( NoSLs ) substantially affected the liquefaction resistance of stratified structures: as NoSLs increased from 1 to 3 layers, the cyclic resistance ratio was reduced by 20%, 10%, and 7% for FC values of 20%, 30%, and 40%, respectively. The liquefaction resistance of the stratified samples was greater than that of USM. . To quantify the effect of silt uniformity and NoSLs, the nonuniformity index ( NUI ) was introduced herein; the calculated NUI values showed that the increase in liquefaction resistance was well correlated with the increase in the NUI.