Cellular Pier Rehabilitation Design-PPT Presentation

PPT Presentation

Pdf Summary

Pier #3 at Bath Iron Works in Bath, Maine, is a 642-foot-long, 48-foot-wide pier built in the 1960s. Its cellular steel sheet-pile walls had deteriorated significantly, with corrosion holes and loss of fill. Crane-support piles were critically corroded, prompting suspension of crane service in August 2019.<br /><br />Emergency repairs installed micropiles to strengthen the crane supports, patched the sheet piles, and backfilled cells with flowable fill. Crane service resumed in February 2021. In parallel, engineers assessed the cells’ remaining capacity using ultrasonic thickness measurements, hand calculations, and a calibrated PLAXIS model. Although the cells did not meet modern recommended safety factors, they could continue confining the deck and crane piles if protected from further deterioration.<br /><br />The permanent rehabilitation was designed to shield the existing cells and reduce lateral loads. The selected system combined NZ-42 sheet piling, concrete-filled pipe piles drilled into bedrock as integrated toe pins, internal tiebacks anchored to the existing cells, a wale, and concrete backfill placed in lifts. The alleyway between Pier #3 and the adjacent facility was also filled with concrete, supported by small H-piles, with cellular foam concrete used to limit displacement of underlying organic soils.<br /><br />Construction included installing the pipe piles and sheet piling, drilling the piles into bedrock, adding tiebacks and the wale, and placing backfill and a new concrete deck. The work was completed in February 2023 at an estimated cost of $39 million. Pier #3 returned to service in March 2023.

Keywords

Bath Iron Works

Pier 3

Maine

steel sheet-pile walls

corrosion

micropiles

ultrasonic thickness measurements

PLAXIS model

tiebacks

rehabilitation