SUPPLEMENTAL HELICAL TIEBACK INSTALLATIONPROJECT INFORMATION
In May of 2018, Coastal Foundation Solutions was contracted to install supplemental helical tiebacks to aid in preventing further decay and disruption to our client’s existing concrete seawall.
EXISTING ISSUES
The Owners were concerned about their existing aging concrete seawall due to several seawall failures, directly correlated too Hurricane Irma. This project had numerous manufactured homes in the community situated within ten (10) feet of the existing seawall. The conventional concrete deadman were not a viable solution, due to extensive disruption of the upland property and proximity of homes. Additionally, the project already contained pre-stressed concrete soldier/king piles from a previous repair.
This project consisted of 2,809 lineal feet of shoreline located in Naples, Florida. The existing seawall was in fair condition. There were certain elements of concrete spalling along the seawall cap that were cracked and fractured. In addition, the concrete King Piling were showing small gradations of salt water intrusion and spalling.
The existing tie-back anchors were considered to be in fair to poor condition. Upon visual inspection numerous existing tie-back anchors were entirely corroded and decayed. The balance of existing tie backs exhibited visual traces of significant rust decomposition and there were multiple locations along the wall that were slightly out of alignment.
PROJECT RECOMMENDATIONS
To install one hundred ninety-eight (198) supplementary helical tieback anchors. The installation of theses anchors will prevent further decay and disruption in the existing seawall.
HELICAL TIEBACK INSTALLATIONTHE SOLUTION
Naples Land Yacht Harbor, located in North Naples, Florida in May 2018 awarded Coastal Foundation Solutions a contract for the installation of one hundred ninety-eight (198) supplementary helical tieback anchors. Coastal Foundation Solutions along with Turrell Hall and Associates designed a system to prevent any further movement to the existing concrete seawall and provide stabilization to the structure. A Seawall Saver Helical Tie-Back anchor system was chosen by the owner, contractor, and engineer as the desired method to stabilize the seawall structure. The system was installed by Coastal Foundation Solutions (CFS), a Certified Installer of Seawall Saver Helical Foundations Systems headquartered in Matlacha, Florida.
Due to the proximity of the homes to the seawall (10 feet), access was severely constrained. The project entailed utilization of a specialized barge to provide water accessibility to the seawall structure for designated repairs.
One Hundred Ninety-Eight (198) Seawall Saver SS125 (1-1/4-inch square bar) helical tieback anchors with a 6”x6”x6” triple-helix lead section was installed through a six-inch diameter cavity opening. Coastal Foundation Solutions utilized combinations of specialized concrete core bits to gain access through existing 8” thick vertical seawall. The 2019 Kubota KX040 excavator with a specialized mast system powered by a 6K Pro-Dig drive head was utilized to install the anchors. Seawall Saver helical extensions imbedded the tieback anchors to lengths of 15 to 21 feet to attain final installation torques. The cavity was filled with a 6” polystyrene foam plug and a H.D.E.P. membrane to prevent soil loss.
The helical tieback anchors were hydraulically rotated to 2,000 P.S.I., providing a tension load of 12 kips.
Two Hundred Sixty-Four (264) additional SS125 extensions were used to attain dynamic load capacity due to sub-surface soil disparities.
The helical tie back anchor was linked to a hot dipped galvanized steel channel, placed at the outside wall face to provide lateral structural support. All tiebacks and anchors were load testing with a 30-ton center pull ram to secure required engineered load capacity.
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