Installation, Load-Testing and Design of Geo-Jet® Soil-Cement Piles

Deep mixing techniques for mass ground improvement are now widely accepted and are used most commonly for bearing capacity enhancement, liquefaction mitigation, and for slope stabilization. The employment of secant soil-cement columns, alternately with and without a steel profile inserted, is also well-known in the industry, the Central Artery & Tunnel Project ("Big Dig") in Boston being the most notable example of such an application here in the United States. However, the use of individual soil-cement columns for load-bearing purposes while less common is no less adaptable, either with steel reinforcement or without, and this paper will describe the particular merits of the patented Geo-Jet system of deep mixing for such an application including consideration of design issues, testing and installation. Case histories of vertically loaded soil-cement columns using the patented Geo-Jet system, including projects such as San Francisco International Airport, and the Millbrae BART Station and other projects in the Bay Area, will also be described.