Determining Concrete Cast-in-pile Depth
Determining Concrete Cast-in-pile Depth
(OP)
Okay, I'm looking for suggestions. Our city is having difficult with residential foundation contractors not installing concrete cast-in-place piles to the specified depth. There are no inspections during the installation of the piles by the city.
Are there any instruments or methods of determining pile depth after casting? A good example is a 10"dia x 15ft deep or 18 ft deep pile being commonly installed to a depth of 10-12ft. We just dugg up a "18ft deep pile" that had failed which turned out to only be 6ft deep. Go figure.
Other than being everywhere at once, and standing beside everyhole in the city with a tape measure. Any thoughts?
Are there any instruments or methods of determining pile depth after casting? A good example is a 10"dia x 15ft deep or 18 ft deep pile being commonly installed to a depth of 10-12ft. We just dugg up a "18ft deep pile" that had failed which turned out to only be 6ft deep. Go figure.
Other than being everywhere at once, and standing beside everyhole in the city with a tape measure. Any thoughts?






RE: Determining Concrete Cast-in-pile Depth
There are lots of ways for a Contractor to cheat, but it is a deterrent and provides a "paper trail" if legal action against the Contractor is taken later.
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RE: Determining Concrete Cast-in-pile Depth
RE: Determining Concrete Cast-in-pile Depth
They might be able to defeat the inspection by ramming the tube down to 18' and pouring concrete down to only 6. If that's a concern, then have them install 2 pvc pipes with two 90 degree elbows on the bottom next to the column. Then you do two tests -- 1 to check for depth and another to check for continuity between the two pipes. At that point, it's possible for them to cheat, but it would probably be more effort to cheat than it would be to do it right.
Crazy? Hare-brained? Maybe. But it's cheap and the good thing about being in the government is that you get to write the rules.
Engineering is not the science behind building things. It is the science behind not building things.
RE: Determining Concrete Cast-in-pile Depth
i wouldn't trust batch tickets...tickets can be fabricated with no problem and i know that it happens regularly. and there are non-destructive methods to estimate the length and integrity but they are relative expensive, time consuming and in this case, not appropriate.
but given that it is after the fact and apparent that the contractor is cheating...i would make the contractor (at their cost) pay to have the a geotechnical engineering firm drill/core a hole through the center of the pile and determine the length. if more than a few came up short, then i think the entire bunch should be rejected at the contractor's expense.
and i'd like to see how someone in this situation came to the conclusion that piles were necessary. and as far as keeping it cheap, i wonder how much it will cost the unknowing home owners once they have a problem. their insurance will likely not be willing to pay and they will have an uphill fight with the developer in court. not to be preachy here, but it sort of defeats our obligations to look out for the public when this sort of thing happens.
RE: Determining Concrete Cast-in-pile Depth
RE: Determining Concrete Cast-in-pile Depth
http://www.pile.com/grl/offices/illinois.asp
RE: Determining Concrete Cast-in-pile Depth
http://www.pile.com/grl/services/it/default.asp
RE: Determining Concrete Cast-in-pile Depth
here's link that does pretty good at describing the different methods.
http://olsonengineering.com/2007site/index.php
but again, for things like this, it will be faster, more "definite", and maybe cheaper to stick an air track (pneumatic) drill on top of the pile and drill until you bust through the bottom. these drills are the kind used to drill hole for blasting. it'll leave a ~2.5-4" hole. then grout after taking measurement. around my part, you can rent these buy the day then hire a geotech to stand there as well (again, i'd have the contractor pay for these services...but the EOR or BO should first approve the firm watching the drilling).
keep in mind that this still does not do anything to verify the reinforcement is in the pile and there is no method i am aware of that can check rebar in a pile.
i'm still trying to figure out how the required depth was determined in the first place. either way, i hate to be the doom and gloom guy here but i personally would have serious reservations about this whole scenario. good luck.