MEASUREMENT OF PILE SET AND IMPACT VELOCITY FOR DRIVEN PILE ACCEPTANCE-PPT Presentation

PPT Presentation

Pdf Summary

Driven-pile projects typically use static and dynamic load testing on only a small portion of piles, leaving 90–97% untested. Driving formulas are commonly used to assess those piles, but their reliability can be limited by inaccurate blow-count-based set measurements, unmeasured temporary compression, overestimation of static capacity, and assumptions that hammer efficiency remains constant.<br /><br />Hammer performance and energy delivered to the pile can vary throughout a project. The presentation proposes measuring peak pile velocity (VMX) as a proxy for peak impact force and delivered energy, alongside pile displacement. Non-contact monitoring with a high-speed camera can safely and accurately measure set and temporary compression for each blow, while velocity measurements help account for changes in hammer performance and cushion condition.<br /><br />The proposed acceptance process uses dynamic testing and wave-matching analysis on selected initial piles to establish both a target set and a corresponding minimum impact velocity. Untested piles are then driven until they meet both criteria. This improves on the conventional approach, which sets a target based on pile set alone and does not account for variable hammer performance. The authors suggest that the enhanced method could increase foundation reliability and potentially allow less conservative designs, reducing pile dimensions or lengths.

Keywords

driven piles

load testing

driving formulas

blow count

hammer efficiency

peak pile velocity

VMX

pile displacement

wave matching analysis

foundation reliability