Innovative Pile Extraction Technique of CFA Piles for the New Harbor Bridge Project-Paper

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The New Harbor Bridge project in Corpus Christi, Texas, includes a cable-stayed bridge supported by large-diameter drilled shafts. At the north tower, 3 m diameter, 75 m deep shafts conflicted with existing 20 m-long CFA/ACIP piles installed for a former warehouse. Because the piles contained substantial reinforcing steel near their tops, they had to be removed intact rather than drilled through.<br /><br />The piles were installed in layered ground: loose sand, very soft clay, variable sand, and stiff clay. These conditions had produced substantial variation in pile diameter and shape, which could not be reliably predicted before extraction.<br /><br />To remove the piles efficiently, the project team developed a wet rotary coring method combining hanging-lead CFA drilling equipment with a drilled-shaft bentonite slurry system. A large-diameter core barrel was advanced around each pile while bentonite slurry was circulated and recovered for reuse. The hanging leads helped the tool follow each pile’s position and shape.<br /><br />Although many extracted piles were relatively straight and smooth, others had one-sided bulges, significant bends, or sharply varying diameters. Measured diameters ranged from about 330 to 600 mm, compared with the nominal 400 mm. Some piles appeared to curve continuously rather than change direction abruptly.<br /><br />The work demonstrated an effective way to remove reinforced CFA piles that obstruct new foundations. It also highlighted the importance of quality control and quality assurance during pile installation, particularly in soft soils. The authors note that modern monitoring and thermal integrity profiling can provide better information about pile shape and diameter with depth.

Keywords

New Harbor Bridge

Corpus Christi

cable-stayed bridge

drilled shafts

CFA piles

ACIP piles

wet rotary coring

bentonite slurry

pile extraction

quality control