Removing old Concrete Piles

[OSUCivlEng]

Does anyone know if it's even possible to remove existing concrete piles? The piles are 16" square in three rows of 6 on 3'-0" centers. I've seen old steel H-Piles be removed, but I'm not sure the concrete piles would come out in one piece.

I am designing a grade crossing to replace an existing bridge, and the existing center pier is on reinforced concrete piles. Ideally it would be nice if the drilled shafts for the new pier could be placed where the piles are now. Otherwise I'll just straddle the piles with the shafts and put a large grade beam over the top.

 

[SlideRuleEra]

Yes, concrete piling can be successfully extracted. One traditional way is the drive the pile a few inches deeper to break the skin friction. Then use a vibratory hammer to pull upward. Connecting the hammer to the pile to withstand the uplift can take ingenuity and is not always possible. Of course, this technique may not work at all for point bearing piling. Success rate varies depending on soil conditions, but it is an inexpensive method to try.

If the piling are in or near water, jetting around the pile can allow extraction. Probably not useful for your project.

A more appropriate method may be to drive a steel pipe around the existing pile. Then drive a larger steel pipe around the first pipe. The outer pipe will break the soil's skin friction with the inner pipe. This allows extraction of the inner pipe, which should also remove the piling at the same time. I have no experience with this method, but see this link for a summary of an actual project:

http://dcpuk.com/images/library/files/pdf/Concrete_Pile_Extraction.pdf

For your project, the outer pipe may be a suitable form for a new cast-in-place piling.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[OSUCivlEng]

That's a innovative way to remove concrete piles, but I can't see the DOT going for that.

I'm fairly certain these piles were point bearing since they were driven to rock. Like you said attaching the hammer to the pile and making sure it comes out in one piece could be problematic.

 

[CELinOttawa]

If I may ask, why would you need to remove them at all? If they were driven to rock, could you not supplement with additional piles in order to achieve an increased capacity?

Just curious; I've never found myself needing to remove a pile...

 

[OSUCivlEng]

If it were up to me I would just reuse them and add additional piles as necessary. However it's not my decision to make even though I'm the one designing the bridge.

For some reason the DOT doesn't like to reuse old piling for new bridges. I'm not sure what their reason is, but I guess they think if they are going to build a new bridge then the foundation should be new as well.

I ran into this same problem on another project except it was a spread footing for an old pier. They made me straddle the footing with drilled shafts and put a grade beam over it.

 

[CELinOttawa]

This just sounds stupid... Frankly I'm no Geotech, but won't you be disturbing the soil, f'ing with the overconsolidation (etc!) and just all around making this difficult to work with? Thank God you're going to bedrock...

Sounds like a prime example of a failure to be environmentally friendly. I don't care if people don't often think about it this way, but you're throwing away money, and while I suspect your a Yank (so it is not any of my colourful Canadian or Kiwi money), the principle is the same.

Go find a small 'c' Conservative politician to get on board. Fix the issue for good. Then again, I can sympathise that your bread may be buttered by the very people requiring you to behave stupidly.

Yes, I have been drinking. lol/sigh/oh god not another diaper/just sleep already/can I go back to the office now?

 

[OSUCivlEng]

Yeah these guys are pretty conservative with their engineering (not sure about their politics). All drilled shafts go to bedrock and only the end bearing and friction in the rock counts towards resistance. Most of the soil in the state is clay and not really suitable for foundations supporting bridge size loads. I understand their conservative mindset when dealing with rivers and creeks because of the unpredictability of scour, but not for overpasses.

It's frustrating at times, but you are correct about them buttering my bread. Gotta do what they want to do if you want to keep working for them. The client is always right even when their wrong.

 

[BigHarvey]

Another solution is to extract them with a diaphragm wall grab. You excavate a barrette 2,2 m long centerd on the pile, even if the pile breaks, you cna keep on with the excavation until you remove everything. I've done it once to remove precast driven concrete piles right on the way of a diaphragm wall to be constructed. It worked very well. I've also seen the second method described by oldestguy work in one occasion.

 

[engidude]

Very insightful discussion in addition to engineering