How to Evaluate an Existing Open-End Pipe-Pile via FHWA Nordlund Method?

[Beanbag1]

Greetings fellow engineers,

I am in need of simplified advice in regards to estimating (via hand calculation) the side resistance strength of an existing drive 14-inch OD Open-End pipe pile in sand, using the FHWA Nordlund method.

Let's assume this to be a non-displacement pile and it's embedment length is approximately 40-feet.

I am aware that Nordlund provides a graph line "a" for Closed-End pipe piles (displacement pile) and graph line "f" for H-Piles (non-displacement pile), but no graph for an Open-End pipe pile, which puts me in a conundrum. I am aware that there are other methodologies to choose from, but am curious as to how to handle this problem via the use of the FHWA guidelines.

Thus, here is the question: In order to obtain the estimated side resistance strength, if I use Nordlund's H-Pile graph line "f" for this Open-End pipe pile, along with using only the exterior surface area of the pipe (discounting the interior surface area of the pipe), will I obtain a reasonable estimate of the pile's side resistance strength? If not, then how can I use the Nordlund method for this problem?

Thank you,

 

[Kevin9679]

If you perform your calculation as you described, assuming you do everything else correctly, you may end up with a very conservative design.

 

[geotechguy1]

Is there a reason you have to use the nordlund method? I don't think open ended piles were included in the database used to develop the method so unless you have a paper or something that extends it to open ended piles I would use one of the other methods to estimate the side resistance. I think the FHWA manual describes a couple of alternatives you could use for cohesionless soils that would be fit for purpose