Steel pile into soil?

[carsonwjohnson]

I have a client who's building a ground mount solar array, but instead of using concrete for his foundation, he's wanting to drive the posts straight into the ground. I'm looking in the IBC, but all I'm seeing is testing methods. Is there a code-based calculation somewhere that I'm missing, or is this something that will end up being more trouble than it's worth for the client?

 

[SlideRuleEra]

What your client is requesting is very common in the bridge business, nothing wrong with it. For bridge work, it is common to require 10' as the minimum H-Pile penetration into soil.

Here is a photo of a typical bridge using this method:

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[carsonwjohnson]

Yeah I understand it's something that can be done, but I'm trying to figure out if there's a way for me to calculate it without specific testing of the site. If they need soil testing, then it's not cost effective and they'll just pour flagpole footings.

 

[jayrod12]

wouldn't you want soil testing for the flagpole style footings anyway? You can make the same style of assumptions and design for the ground driven into the ground or make assumptions and design a flagpole footing. I fail to see the difference.

 

[jike]

You might consider using helical anchors, depending upon soil conditions.

 

[BigH]

It all depends on the soil . . . - each of the above have acknowledged that you need to have some soil properties . . . contact a local geotechnical engineer - he may have some nearby data and geological experience and be able to help you out without a full blown investigation.

 

[BigH]

BTW - nice picture SRE!

 

[BUGGAR]

You can relate blow counts on the pile with its allowable capacity. You will have to know the pile hammer specs. I've used this on drop-hammers as well.

I did some small diameter pin piles once (3" dia. stnd. pipe). The geotech gave us a chart of pile capacity vs. penetration per minute driving with a 90 lb. jackhammer. This worked well but I've never seen a geotech do this before.