Modernization of Newport International Terminal Docks

Context

Two former World War II concrete cargo vessels serve as the dock foundation. The very robust vessels were manufactured from concrete due to the scarcity of steel during the war and were purposefully sunk in place in the late 1940’s.

Within the scope of the modernization work, each sunken vessel was surrounded by a coffer dam made by steel sheet piles. The outer sheet piles are tied to the inner piles through the vessels by double corrosion protected (DCP) DYWIDAG Tie Rods. In addition, the inner piles are tied to a cast-in-place reinforced concrete dead-man pile cap with additional DCP DYWIDAG Tie Rods.

The dead-man wall, in turn, is tied back to stable ground by DCP DYWIDAG Strand Anchors and supported at the toe, facing the sheet piles, by uncoated DYWIDAG Micropiles.

Solution

DYWIDAG supplied the following products for this unique project:

• 24 6-0.6" DCP DYWIDAG Strand Anchors in lengths of 30.5m to 33.5m (100ft to 110ft)

• 19 2.5" Grade 150 and 3.0" Grade 150 DCP DYWIDAG Tie Rods in lengths of 16.76m to 22.86m (55ft to 75ft)

• 21 57mm Grade 75 DYWIDAG Micropiles in lengths of 13.72m to 19.81m (45ft to 65ft).

DBM Contractors was responsible for designing and installing the 21 micropiles which acted as vertical and lateral support for the cast in place dead man. Once the micropiles had been installed, the concrete dead man was concreted with blockouts for the tierods and tieback anchors. After the cast in place pile cap had cured, DBM installed the DCP tieback anchors.They acted as the primary lateral support for the DYWIDAG Tie Rods, which were the last elements to be installed.

The installation of the tie rods presented a challenge because they had to be installed through holes in the existing concrete ships. In addition, some DYWIDAG Tie Rods extended through the sheet pile wall to a waler system that could only be accessed during low tide. After all the elements had been installed, the tie rods were tensioned to a nominal load using a hydraulic tensioning jack and locked off. Afterwards, the tieback anchor system was stressed to ensure that the sheet pile wall did not deflect during placement of the backfill.

Thanks to the close coordination between all of the companies involved, work on this project was completed meeting all design criteria within the defined time frame.