Harden Blvd. Access Road Stabilization Design - Polk County intended to construct an approximately 600 foot long access road that progresses east from Harden Blvd. to provide access to a new development (residential and/or commercial) in Lakeland, Florida.  The proposed alignment passes through former phosphate mined lands that have undergone varying degrees of reclamation and approximately 2/3 of the alignment included very soft waste phosphatic clay deposits near the surface and to depths of up to 35 feet.  MEG was requested to provide a geotechnical design to provide a stable, permanent platform for roadway embankment construction along the proposed access road alignment.  MEG’s design included CSV columns combined with a load transfer blanket (LTB) consisting of multiple layers of biaxial geogrid interbedded with compacted sandy fill.  The system will distribute and transfer roadway, embankment, and vehicle loads to more competent soils at depth.  CSV stands for “cement stabilized vertical” columns, and is an in situ stabilization method which essentially provides a rigid vertical element through the soft soil much like a pile with an added benefit of improving the soil mass within the CSV treated area also.  The LTB acts much like a bridge deck and transfers the more uniform embankment loads above it through the LTB into the individual CSV columns below it.  The LTB must be stiff enough to transfer the point loads “created” by the resistance (load carrying capability) of the CSV columns laterally and vertically without punching through it.  The combined system provides a more uniform load response to the roadway embankment.  The roadway stabilization, as designed, was estimated to cost about $750,000 to construct.


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