Written by Barkley Matthews, PE on August 11, 2021
Hurricane Sally left a path of destruction across Alabama including this residence that was constructed on a bluff overlooking Perdido Bay. The seawall protecting the home failed during the storm and washed portions of the yard into the bay. The rear of the house saw extensive foundation damage that left the foundation completely exposed and partially undermined. This damage left the house susceptible to further foundation settlement and major structural damage. Access could only be gained by water and vibration from equipment or installation of piling could possibly further erode the foundation. Based on these site conditions it was determined that small equipment and helical piles were the best choice for foundation remediation.
Installation of CHANCE RS2875.276 helical piles with the C1500121 CHANCE Standard Underpinning Brackets were completed by local installer Mason Grady Foundations. A mini excavator was brought to the site on a barge from Perdido Bay. In total 15 helical piles were installed to a depth of 25 feet into the underlying bearing stratum. Due to the excessive pile reveal required, column buckling was a concern at the pile head connection. To provide additional lateral support a 6” diameter PVC sleeve reinforced internally with a rebar cage and filled with structural grout was placed around the top section of each helical pipe shaft.
Despite the access and site conditions Mason Grady Foundations was able to successfully stabilize this home in five days. The expedient install of the CHANCE underpinning systems was vital in keeping the home from having further structural damage. A new tieback seawall is planned to be constructed along Perdido Bay. This seawall will use CHANCE helical tiebacks to restrain the wall and offer enhanced protection from future natural disasters.
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