Helical Piles - Model 288

Project: Gaines St. Corridor Reconstruction

Location:Tallahassee, FL

Date:April 2011

Installed rows of helical piers

Helical piers installed vertically and battered

Helical pile new construction bracket embedded in rebar cage

Finished footing

Challenge:

Gaines St. needed to be widened to sustain traffic growth; however a large oak tree adjacent to the road required a retaining wall to be installed to preserve the tree. Due to the large root-ball of the oak tree a typical cantilevered retaining wall design was not practical. There was only a work area approximately 10' wide between the tree and the road and many above ground and underground obstructions including gas, water, electric, and data cables all passing under or over the work area.

Contacted Alpha Foundation Specialists for an expert foundation repair consultation.

Solution:

Due to limited access Garcia Bridge Engineers decided helical piles were the best option. A helical pile configuration consisting of a 2-7/8 inch outside diameter round shaft with a 10"-12" double-helix lead section was selected. Each of the piles were installed with a drive head attached to a Bobcat E35 and were installed to a minimum of 6,000 foot/pounds of torque. Each helical pile was advanced to an embedment depth of 14' below grade. Each pile was attached to the footing with a Foundation Support Works new construction bracket. The ultimate capacity of the production piles was monitored during installation with different PSI gauges. The correlation between installation torque and ultimate capacity was verified by performing two load tests and one proof test at the Structural Engineers selection. All piles tested exceeded all necessary requirements. The installation of 46 helical piles took only 2 days to complete.

Project Summary

Structural Engineer: Garcia Bridge Engineers
General Contractor: Sandco, Inc.
Certified Installer: Alpha Foundation Specialists, Inc.
Products Installed: (46) Model 288 Helical Piles, 10" - 12" lead section, installed to depths of 14' 25 kip design load.

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