Case Studies To Determining Pile Compressive Capacity Using Vibratory Hammer Equipment For Installation-PPT Presentation

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The presentation examines how timber piles installed with vibratory hammers can be certified for compressive capacity, despite limited industry guidance and weak correlations between vibratory installation data and pile capacity.<br /><br />The proposed approach combines vibratory and impact hammers in a test-pile program. Piles are first installed with a vibratory hammer to a defined depth or practical refusal, then driven further with an impact hammer to establish capacity using an accepted criterion. If the test piles meet the required capacity, the vibratory installation procedure can be approved for production piles.<br /><br />Two New Jersey projects illustrate the method. At Brant Beach, test piles were predrilled and driven with an impact hammer to establish criteria; production piles were vibrated to the target depth and finished with impact driving. At Beach Haven, test piles were vibrated to practical refusal and then impact-driven to the required capacity; production piles were installed with vibratory hammers to practical refusal.<br /><br />Vibratory hammers can reduce installation time and equipment costs, but their capacity estimates are limited by equipment and soil variability, operator and record-keeping requirements, and the absence of an accepted industry standard. Impact hammers are better documented and can achieve higher capacities, but are more costly and disruptive.<br /><br />The authors conclude that vibratory-only installation cannot reliably support capacity certification. A combined-hammer test-pile program is the preferred approach, with instrumentation such as PDA or static load testing recommended to improve understanding and capacity correlations.

Keywords

timber piles

vibratory hammers

compressive capacity

impact hammer

test-pile program

pile certification

New Jersey projects

practical refusal

pile driving criteria

pile load testing