New Graving Dry Dock at Tampa, Florida

A graving dry dock, 900 ft (280 m) long by 150 ft (46 m) wide by 26 ft (8 m) deep, has recently been completed in Tampa, Fla., in which hydrostatic uplift pressures are semirelieved by a plastic pipe system embedded in the bottom slab and a deeply driven perimeter wall of steel sheetpiling. Welded steel studs transfer shear from the concrete to the piling so that the piling also serves as tension reinforcement for cantilever wall action of the side walls and end-wall of the dock. The construction method used an inner row of sheetpiling, about 25 ft (8 m) from each outer row. Temporary bracing allowed excavation between the two rows so that the edge section of the slab and the wall could be poured. These elements then acted as a retaining wall for the remainder of the excavation. A 300-ton (270,000 kg) steel hinge-type dry dock gate was fabricated elsewhere and set in place in one piece.