This article describes the selection, design and installation of 265 new steel screw grout injection ('Tubex') piles for an existing 12 lane, 180m main span bridge carrying the A12 motorway over the Amsterdam-Rhine Canal. Renovation of the bridge including addition of steel box girders and jacking up of the deck by 1.2m required new foundations to carry design loads up to 35MN adjacent to and between existing bridge piers. The new foundations were installed under low headroom and close to existing foundations and canal walls and in places through existing pile caps. The means of assessing additional settlement effects on the existing pile caps is described. Permanent pile casings and coring through the existing pile caps were used to prevent lateral load transfer to the existing pile caps or canal walls. Installation of the piles through approximately 25m of medium to very dense sand was challenging. Grouting over the full length of segmented piles was innovatively applied on this project. Back-analyses of ground stiffnesses from preliminary trial pile tests and foundation performance in service are presented and correlated with CPT test results.
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