I was told at pile penetration resistances over around 10BL/in. you are likely not fully mobilizing and your PDA is likely under predicting your capacity. Can anyone confirm or deny this? Does anyone know of any good sources of research on this topic?
Not sure of the actual answer here but based my experience the PDA is usually conservative with H-piles driven to shale bedrock. I’ve had people tell me that the PDA is usually conservative in general.
I had a project with HP12s and HP14s driven 120+ feet down to shale. We PDA’d one of each and then performed a static load test.
The final blows for the HP14x89 were 10-8-11-12, PDA capacity at end of driving was around 680 kips, re-strike the next day was 700 kips, and the static load test was 920-1000 kips (based on Davisson’s criterion).
The final blows of the HP12x74 were 6-10-9-9, PDA capacity at the end of driving was 585 kips, re-strike the next day was 575 kips, and the static load test was 612-640 kips.
We PDA’d several more piles on the project but didn’t load test them. HP12x74 PDA results ranged from 540 to 640 kips. HP14x89 ranged from 675 to 820 kips.
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