Site Improvements with Stone Columns in Stratified Silty Soils

A case history is presented where stone columns were used as a deep compaction method to increase the liquefaction resistance of stratified silty soils. Standard penetration test (SPT) and cone penetration test (CPT) resistances were used to evaluate the pre-treatment site conditions and post-treatment effects of deep compaction using stone columns. The results of the deep compaction are presented with predicted penetration resistances required to reduce the potential for liquefaction. Limitations of conventional liquefaction analysis in silty soils are discussed with regard to SPT-CPT correlations established for the site, cyclic simple shear tests performed on silts, and corrections to SPT penetration resistances for fines content