PDA High Strain Dynamic Load Test / Pile Driving Analyzer 1

[struggle67]

Hi everyone

Any PDA expert here? Is PDA reliable? Can someone please recommend any literature on PDA or any work examples to calculate pile soil resistance from PDA results?

I also came across this formula below. Quite a lot of questions popped into my head.

How was this formula derived? What do the 1st term force term and 2nd velocity x pile impedance represent? I understand that F(t1)can be obtained from the strain gauge attached near the top of the pile but how do I get this F(t1+2L/c) value? Why are two forces in the first term added, two velocities subtracted and divided by two?

Thanks for your sharing in advance

 

[geotechguy1]

That particular equation is explained here: (

https://www.pile.com/wp-content/uploads/2017/03/CaseMethod.pdf)

you can also check out other relevant references here:

https://www.pile.com/resource-type/reference-paper/page/28/

Usually you'd hire someone who specializes in doing the testing and interpreting the results.

 

[struggle67]

Thanks, Geotechguy1

Yes, we'd get someone to do but just wanted to know the reliability and to have a bit of understanding of the test results submitted.

 

[geotechguy1]

On some bigger projects I was involved in (think $20 billion mining projects with 20-50,000 20m long piles) during the investigation phase a program of test piles, static pile load tests, and PDA testing would be performed. Then during construction only PDA testing. Personally I don't think this is really necassary particularly if you are doing a large number of PDA tests (i.e. 5% PDA testing an 0 static load tests is in my opinion better than 2% PDA testing and 1 static load test). I have never been able to find any evidence of case histories where a failure occured because the capacity predicted by PDA was much higher than actual capacity, although I suppose that doesn't mean it's never happened.