Large Diameter Open-End Pipe Pile Driveability Analysis Including Geotechnical Friction Fatigue-Paper

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The paper evaluates how geotechnical friction fatigue affects the driveability of large-diameter, open-ended pipe piles. Friction fatigue is the progressive loss of shaft resistance caused by repeated soil shearing as a pile is driven. The study compares two wave-equation analyses for offshore piles: an Alm and Hamre friction-fatigue model based on cone penetration test data (FF), and a conventional model using soil set-up factors (SD). Both analyses assumed fully coring conditions.<br /><br />For the case study, the FF model predicted a substantial reduction in shaft resistance during driving, including an average 54.4% decrease in static resistance during driving. At final penetration, its predicted total shaft resistance was about 84% lower than the SD model’s. Dynamic measurements also showed lower resistance than either prediction, but were closer to the FF results.<br /><br />The FF model predicted blowcounts averaging 6.4% below those recorded during installation, while the SD model overpredicted them by 42.1%. Unlike the SD model, which predicted a rapid, exponential rise in blowcounts with depth, the FF model better reproduced the relatively steady blowcount pattern observed at deeper penetrations. The study suggests that conventional set-up factors derived from shorter onshore piles may not represent marine soil conditions well.<br /><br />The authors conclude that friction fatigue should be considered when analyzing deeply driven, large-diameter open-ended piles, and recommend using CPT-based friction-fatigue analysis under a fully coring assumption. The study focuses on shaft-resistance loss and does not model plugging, although the observed driving behavior was consistent with coring and indicated that partial plugging may develop briefly.

Keywords

geotechnical friction fatigue

pipe piles

driveability

shaft resistance

wave-equation analysis

cone penetration test

Alm and Hamre model

soil set-up factors

open-ended piles

blowcounts