The Driving and Capacities of Coated and Non-Coated Piles in Pacific Northwest Fine-Grained Alluvium

PPT Presentation

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The case study examines the driving and capacity of coated and uncoated piles for the I-205 Abernethy Bridge widening in Clackamas County, Oregon. More than 200 piles were installed to support a temporary trestle and drilled-shaft operations, including trestle, battered, and oscillator piles.<br /><br />Coated trestle piles were generally 36-inch-diameter, thin-wall steel and were installed to depths of up to 160 feet, with a required ultimate capacity of 1,800 kips. Uncoated oscillator and battered piles had thicker walls, reached depths of up to 170 feet, and required a 2,800-kip ultimate capacity. Subsurface conditions varied across the site, comprising gravel alluvium over sand and fine-grained alluvium, with decomposed, weathered, and competent basalt below.<br /><br />Thirty-one pile driving analyses (PDAs) were conducted on 24 piles, at end of initial drive and during setup periods of up to six days. Results generally showed lower skin resistance than anticipated. Most strength gain from setup occurred within three to four days. PDA findings helped refine driving criteria and allowed some piles to be installed at shallower depths than originally planned, rather than driven to refusal.<br /><br />The study found PDAs valuable for confirming capacity and adjusting installation criteria. Hammer selection had a substantial effect: the APE D100 generally performed well, while the D138 was considered too powerful for trestle piles but better suited to oscillator piles. The presentation does not establish a definitive coated-versus-uncoated capacity difference; it recommends further research on coating durability, long-term pile strength, and more consistent testing with the same hammer types.

Keywords

I-205 Abernethy Bridge

Clackamas County

pile driving analysis

coated piles

uncoated piles

temporary trestle

drilled shafts

ultimate capacity

skin resistance

hammer selection