Driven Pile Capacity Assessment Using Installation Energy and Pile Set-Up

ABSTRACT: This paper describes the process used to verify ultimate pile capacity for a wharf project in Kitimat, British Columbia, Canada. The wharf is in a fjord system, where the Kitimat River meets the Douglas Channel, with a deep foundation supported by open-ended steel pipe piles. The stratigraphy primarily consists of interbedded sands, silty sands, silts and clays. The assessment process first uses hammer energy and penetration per blow to estimate end-of-initial-drive (EOID) pile capacity, based on high strain dynamic testing and static load testing. Then an appropriate set-up factor is applied to the EOID capacity to estimate the long-term capacity of a pile. Set-up refers to the increase of pile capacity over time and is mostly caused by excess porewater pressure dissipation, which is primarily by geology and pile type.