Mitigation of Liquefaction Potential of Silty Sands

Abstract

Mitigation of liquefaction potential of soils with fines contents greater than 15 to 20 percent usually requires special adaptation of the dynamic densification methods — Deep Dynamic Compaction, Explosive Compaction, Vibro-Compaction, Compaction Piles — that are ordinarily used to improve loose, clean cohesionless soils. However, these methods can be used to attain the needed improvement in many soils if closely spaced vertical sand, gravel, or prefabricated (wick) drains are installed prior to construction. Soil-cement columns or walls installed by deep soil mixing or jet grouting can be used to provide both reinforcement and containment of liquefied soil. Removal and replacement of liquefiable silty and clayey soils using compaction, admixture stabilization or substitution by another 'material; e.g., roller compacted concrete, is also possible; however, the cost may be high, and consideration must be given to dewatering needs and the stability of open excavations. Mitigation of the liquefaction potential of high fines content sandy and silty soils using permeation grouting is not feasible because the low hydraulic conductivity of such soils.