Protection of Steel Sheet Pile Bulkhead Using Precast Concrete Veneer

摘要

An industrial yard owned by the United States Army Corps of Engineers (USACE) is located at the Caven Point peninsula in Jersey City, New Jersey. The yard’s berthing waterfront is built in the form of steel a sheet pile bulkhead. The sheet piling, subject to the aggressive salt water environment, has severely corroded since the time of construction in the early 1970s; however, the degree of corrosion of the steel sheeting varied a great deal over the wall height. The most severe corrosion occurred within the tidal zone with its peak being at the Mean Low Water level (MLW). About 15% of the original steel thickness was left at this level. In other zones, where the sheet piling was either permanently dry or permanently submerged, the remaining steel was 80 to 90% of its original thickness. Structural analysis of the bulkhead showed that the maximum bending moment occurs approximately at the level of mudline, where the section loss of the sheet piling due to corrosion was minimal. At the MLW level, where the sheet piling sustained the maximum corrosion loss, the bending moment, on the contrary, was small and the remaining steel thickness was found sufficient to resist it. Consequently, it was determined that the bulkhead in its existing condition was structurally adequate; hence, the goal of its rehabilitation was merely to stop further corrosion and to preserve the sheet piling in its present condition. Protection of the sheet piling has been designed as 20-cm (8-inch) thick precast concrete panels (veneer) installed in front of the existing wall. The space between the sheet piling and the panels would be filled with plain tremie concrete. To make the concrete panels capable of withstanding the lateral pressure of the wet concrete fill, two measures have been proposed: a) use of the lightweight concrete fill, and b) placement of the concrete fill between the sheet piling and panels in several lifts. Each subsequent lift would be placed after concrete in the previous lift has hardened and thus no longer transmits lateral pressure to the panels.