Efficacy of a Combination of Vibro Stone Columns and Vibro Compaction in Layered Soils

Soil liquefaction and associated geotechnical concerns such as high settlements and loss of bearing capacity have been a major source of damage to various structures during past earthquakes (e.g., 1964 Alaska earthquake, 1995 Kobe earthquake, 2001 Bhuj earthquake). Mitigation of liquefaction potential in such soils requires adaptation of ground improvement techniques which use effects such as densification, drainage, and/or reinforcement to improve the natural soil. Application of such ground improvement methods in layered soil shall be assessed carefully as its effectiveness depends on various in situ properties. The present paper discusses three case studies on the application of combination of vibro stone columns and vibro compaction in layered soil (cohesive layer followed by non-cohesive liquefiable layer). A series of pre and post ground improvement soil testing is done to check the efficacy of proposed ground improvement schemes.