TEI ROCK DRILLS EQUIPMENT USED FOR ALASKA PORT CONSTRUCTION
Engineered Piling Installation Required Powerful Drilling Platform
A rugged TEI Rock Drills platform was used to help drive solid and hollow bar IBO rods in the construction of the Halibut Point Marine Multi Use Dock in Sitka, Alaska. This unique deep water port was engineered to accommodate large vessels at a 470 FT x 50 FT floating dock. The facility’s concrete pontoon is attached to float dolphins constructed of four 36 IN diameter pipe piles each. The dock includes an additional breasting dolphin and two mooring dolphins anchored just beyond the floating pontoon.
The typical method for anchoring deep water piling is to drive the pile into bedrock. The ground conditions at Halibut Point made it impossible for the large diameter piles to be driven to an adequate depth. Consequently, the piling had to be anchored to bedrock on the ocean floor.
Marine Structures Engineering and Con-Tech Systems developed an innovative design that integrated 73 mm CTS-TITAN IBO hollow bar tubes in the center of 8 IN casings to affix the dolphins to the bedrock. This engineered configuration produced the advantage of using hollow bars as both a drill rod and grouting conduit.
The steel casings inside the pipe piles extend from the top of the piling down to bedrock. The anchors were then grouted from the bottom up through the hollow bar tube and became primarily passive with an allowable design load of 50% yield.
General contractor McGraw Custom Construction produced a custom drill platform utilizing the TEI feed system and a powerful hydraulic drifter to drill the IBO anchor through the over-burden 15 FT to 20 FT deep into solid rock. The deepest hole was drilled in approximately 140 FT of water. At this depth, there was enough hammering energy to drill 40 FT into the ocean bottom.
Today the Halibut Point Marine Multi Use Dock services the region’s largest vessels including passenger cruise ships and Panamax container carriers.
Portions of this text are reprinted from an article in Piling Industry Canada (PIC) magazine.