PDA Testing and Analysis: Utilizing Test Results with a Focus on Capacity-PPT Presentation

PPT Presentation

Pdf Summary

The presentation explains how dynamic pile testing using a Pile Driving Analyzer (PDA) estimates pile capacity. Strain transducers and accelerometers attached to the pile measure force and velocity signals generated by each hammer blow. Analysis of the stress waves traveling down the pile and returning from resistance allows engineers to estimate total resistance.<br /><br />Because total resistance includes both static and velocity-dependent dynamic resistance, a damping factor is used to estimate the static component from the measured signals and pile-toe velocity. PDA results provide estimates of ultimate compression capacity by depth or hammer-blow number, subject to the selected damping value. CAPWAP signal matching can refine the analysis and distinguish end-bearing resistance from shaft resistance.<br /><br />Capacity estimates depend on mobilizing sufficient pile movement. If the pile’s set per blow is too small, the PDA result may be a lower bound rather than the true ultimate capacity. Engineers should also consider time-dependent changes: setup can increase capacity, while relaxation can reduce it. Restriking the pile after an appropriate waiting period, with an adequately sized impact, helps account for these effects.<br /><br />PDA and CAPWAP results are reported as nominal ultimate resistance, without safety factors. The design engineer applies the appropriate resistance or safety factor. The presentation notes that a resistance factor of 0.65 is typically used when dynamic testing and signal matching are performed on at least two piles per site condition and at least 2% of production piles. This factor may increase to 0.75 when those methods are applied to all production piles.

Keywords

dynamic pile testing

Pile Driving Analyzer

PDA

CAPWAP

pile capacity

strain transducers

accelerometers

stress waves

damping factor

nominal ultimate resistance