Settlement Predictions at a Florida Port Facility

by Thomas E. Selfridge, (A.M.ASCE), Law Engineering, Jacksonville, United States,
Kirk A. McIntosh, (M.ASCE), Law Engineering, Jacksonville, United States,

Document Type: Proceeding Paper

Part of: Vertical and Horizontal Deformations of Foundations and Embankments


A paved container storage area approximately four acres in size has been constructed at the existing Port of Fernandina in Fernandina Beach, Florida. Approximately one-half of the site area originally consisted of a tidal saltwater marsh with exposed very soft silts which extended to depths of over 12 m (40 ft). Due to the planned fill loading (215 kPa [450 psf]) plus container live loading (19 kPa [400 psf]) considerable long term primary and secondary settlements within the silt were anticipated. In order to permit construction, a surcharging program was developed utilizing vertical wick drains to accelerate silt consolidation. In order to predict appropriate rates of fill placement, an iterative procedure was developed which predicted the decrease in water content and corresponding increase in shear strength of the silt as settlement occurred with time. Settlement monitoring data obtained during the surcharging process agreed relatively well with predicted values with a maximum settlement of about 137 cm (42 inches) being measured. The time period for surcharge completion agreed relatively well with the predicted values. It was found that the analytical model developed for this project reasonably predicted the increase in silt shear strength, and allowed construction of the storage area within the allotted time period.

Subject Headings: Shear strength | Soil strength | Soil stabilization | Soil settlement | Consolidated soils | Silt | Load factors | Florida | United States

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