Is it possible to drill through concrete filled steel pipe piles?

[bridgebuster]

I'm reviewing plans for a replacement bridge. Two of the new piers will be at the location of the existing piers. The existing footings are supported by concrete filled 12 inch diameter steel pipe piles. The new piers will be sitting on 4'-6" diameter shafts.

Is it possible to drill through the existing pipe piles? I don't have the original plans in front of me but 20+ years ago when I started the project I recall the piles were closely spaced. I don't think they can be drilled but drilling isn't my area. One spot is low headroom ~20'(-) the other is about 29' headroom. A couple a years ago I seawall replacement project - the contractor had to drill 2'6" holes through cyclopean concrete to install piles and it was a b!+(#.

Thanks in advance for your thoughts.

 

[cvg]

an 8 inch steel pipe shut down Bertha

https://www.seattletimes.com/seattl...t-for-bertha-hitting-pipe-dispute-board-says/

 

[oldestguy]

You might clarify as to size of hole you need. I do know that core drilling with diamond faced "tubes" concrete regularly can be drilled including the re-bars. It might take acetylene or similar torch first to remove the pipe wall.

 

[bridgebuster]

OG - 4'6"

 

[oldestguy]

By "drilling through" do you mean longitudinally, axial, etc.? If so, is there any possibility of extracting the existing piles? Jets of different lengths also needed due to head room limits.

Edit: For adjustable length jests, consider test boring drill rod in the larger diameters. It might even be possible to use a larger test boring drill rig for this.

 

[bridgebuster]

og - It's axial drilling. Perhaps the existing piles will have be get pulled. I have to look at the original plans tomorrow; I don't recall if the piles are keyed into rock.

The bridge is being replaced in three stages but the current plans don't present a suggested sequence. If I were a contractor, I would want to drill as much as I can up front rather than mobilizing and demobilizing over three years. This is one of six bridges in a fairly complex project; while I'm sure their design works they didn't put enough thought into contractibility.

 

[Ron]

If someone can drill a socket of that size into hard rock for a drilled shaft they should be able to drill concrete like that. Tunnel borers also.

 

[aeoliantexan]

Have you considered supplementing the existing piles with additional piles outside the existing group and building a bigger cap? You might also consider drilling micropiles through the existing cap or, in the extreme, down through the pipe piles and farther into the bearing formation. Micropiles would be well suited to the low headroom condition. The pipe piles may have a 3/4-inch or 1-inch bottom plate that could be tough to drill through, but I would guess it could be done.

 

[bridgebuster]

@aeoliantexan - It's not my design and I think it's too late in the game to change the scheme. The existing pier is trapezoidal shaped with piles around the perimeter. The new pier consists of drilled shafts that will support a pier cap. There's one drilled shaft that's going to be in the midst of a bunch of steel pipe piles.

 

[aeoliantexan]

I would think it would be very difficult to auger a 4'-6" hole encompassing one or more steel pipe piles. One might be able to advance a casing with teeth over the piles, wash it out, and cast it. Perhaps the cap design can tolerate a minor shift in the location of that pier to fit the piles. There must be a cheaper way to solve the problem. A few thoughts:
1. See if the bunch of piles in the way have enough capacity to replace the pier.
2. Put the pier outside the pile group and extend the cap out to it.
3. Pull the affected piles, like you mentioned.
4. Draw the pier where you want it and wait for the Contractor to submit a value engineering proposal and split the savings.

A plan and some soil profile details may get you some additional suggestions.

 

[PEinc]

The contractor and/or project owner would probably run out of time and money trying to drill 4'-6" vertical holes through multiple, vertical, concrete-filled, steel pipe piles. Switch the design to small diameter micropiles?

http://www.PeirceEngineering.com

 

[bridgebuster]

thanks for the replies; sorry for the late response; been a hectic week.