Experience with Driven Pile Foundations in California-Paper

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The I-405 Improvement Project in Orange County, California, required driven pile foundations for bridges, retaining walls, and other structures across soft, seismically active ground. The project’s subsurface profile consisted mainly of Holocene alluvial deposits over Pleistocene formations. Cone penetration tests (CPTs), supplemented by boreholes and laboratory testing, provided the primary basis for characterization and design.<br /><br />Pile axial resistance was estimated using the LCPC-CPT method, with adjustments for potential soil plugging in open-ended 24-inch-diameter steel pipe piles. Pile Driving Analyzer measurements and CAPWAP analyses were used to assess resistance at the end of initial driving (EOID) and during restrike, supporting use of Caltrans resistance factors.<br /><br />LCPC predictions generally provided reasonable estimates of measured resistance at the beginning of restrike. Resistance increased over time for both pipe piles and HP18x181 piles. At 30 days after initial driving, estimated dynamic resistance was 150–240% of EOID resistance for pipe piles and 120–180% for H-piles. Pipe piles reached their target capacity sooner. The authors developed project-specific setup factors based on the ratio of EOID resistance to calculated resistance, but caution that these estimates reflect limited data and local ground conditions.<br /><br />The paper concludes that CPT-based design, combined with dynamic monitoring and restrike testing, provided an effective approach for predicting and verifying driven-pile capacity on this project.

Keywords

I-405 Improvement Project

Orange County

California

driven pile foundations

cone penetration tests

LCPC-CPT method

pile driving analyzer

CAPWAP analysis

restrike testing

pile capacity prediction