What correlations can be made from final blow counts for driven piles? 1

[abusementpark]

I've seen where geotechnical engineers set minimum final blow count criteria, as if it is an indicator of final capacity. How are these determinations made?

What if you get great driving resistance at the start but finish with lower resistance?

Are there any good introductory papers on this topic?

 

[Ron]

ABP....pile capacities have been historically related to driving resistance. This is seen in the pile driving formulae such as the ENR, Modified ENR, Janbu and others.
The subject is treated extensively in the literature. As for textbooks, any of the classic geotechnical texts (Terzashi, Sowers, etc.)cover the subject.

There has also been recent discussion here in the forums.

 

[GeoPaveTraffic]

I agree with Ron.

Also, if a WEAP analysis is done relating the soil, pile, hamer, etc. a capacity versus blows per foot curve can be determined.

When we design piles to be driven to refusal, we always indicate a required number of blows per final inch and/or foot to be met.

Mike Lambert

 

[massagung]

its called pile driving formula, to analyze bearing capacity with minimum final set, as i know this formula as known Hiley formula (assume energy transfered), there's still many formula for analyze bearing capacity with minimum final set/blow. but this method is not more reliable.. as we know to analyze bearing capacity for installed driven piles/bored piles accordingly ASTM are HSDT (ASTM D-4945) and ASCLT (ASTM D-1143.

M.A.