Braced Excavation with Crossing Utility Pipe
Braced Excavation with Crossing Utility Pipe
(OP)
Hi all,
I designed a braced excavation (sheet piles with walers and interior struts) and I've just been notified that the utilities that weren't supposed to interfere are now an issue. Basically, they may need to connect the new 4" utility pipe and have it run through the braced excavation.
So, my question, does anyone have experience with staging such an operation and, more importantly, do they need any special details for cutting a 4-6" hole in a sheet where the new pipe will be run?
I figured they could drive the piles to a little above the pipe depth, locally. Excavate to the pipe depth, cut the existing line and mark the pipe elevation, drive the remaining length of the sheet pile, cut the hole in the pile and reconnect the pipe. Is it possible to cut a local hole like this or would any special support be required locally?
Thanks for any suggestions!
I designed a braced excavation (sheet piles with walers and interior struts) and I've just been notified that the utilities that weren't supposed to interfere are now an issue. Basically, they may need to connect the new 4" utility pipe and have it run through the braced excavation.
So, my question, does anyone have experience with staging such an operation and, more importantly, do they need any special details for cutting a 4-6" hole in a sheet where the new pipe will be run?
I figured they could drive the piles to a little above the pipe depth, locally. Excavate to the pipe depth, cut the existing line and mark the pipe elevation, drive the remaining length of the sheet pile, cut the hole in the pile and reconnect the pipe. Is it possible to cut a local hole like this or would any special support be required locally?
Thanks for any suggestions!






RE: Braced Excavation with Crossing Utility Pipe
This probably isn't a big deal depending on the properties of your sheet.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Braced Excavation with Crossing Utility Pipe
RE: Braced Excavation with Crossing Utility Pipe
Racookpe's suggestion is easy and effective but it most likely will be in the way of other forms and such so it most likely can't remain in place.
EIT
www.HowToEngineer.com
RE: Braced Excavation with Crossing Utility Pipe
RE: Braced Excavation with Crossing Utility Pipe
www.PeirceEngineering.com
RE: Braced Excavation with Crossing Utility Pipe
Why not just torch a hole?
EIT
www.HowToEngineer.com
RE: Braced Excavation with Crossing Utility Pipe
Maybe welding a plate or angle above and below the opening to distribute the load to the adjacent piles would work? Just not sure what is typically done in this situation. Another option: burn the hole and put in a small length of steel "casing" pipe through which to run the new connecting utility pipe?
I thought this would be a fairly common issue but it looks like H-piles with timber lagging is typically used if there are utilities. I haven't had much luck searching around online for a typical solution.
RE: Braced Excavation with Crossing Utility Pipe
Usually I've seen a gap in the structure and a wooden sheet substituted which can then be cut around the pipe and sealed with plastic.
Having a high water table and a pipe running thorough your piling is not good, but a 4" pipe shouldn't cause that much grief.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Braced Excavation with Crossing Utility Pipe
RE: Braced Excavation with Crossing Utility Pipe
If you try any other simple seal it will fail after a short period of time.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Braced Excavation with Crossing Utility Pipe
www.PeirceEngineering.com
RE: Braced Excavation with Crossing Utility Pipe
RE: Braced Excavation with Crossing Utility Pipe
Cut the existing pipe, back from the sheet pilling wall. You’ve already got a hole from which to work on the pipe and deal with the hole in the sheet pilling. Drive the full length pilling and cut it off 6" below the pipe. Pull the remaining pilling up 1' or 18", and you’ve got your opening for the pipe re-connection. Then maybe some reinforcing beams at the cut ends onto several sheet pillings on each side of the opening.
RE: Braced Excavation with Crossing Utility Pipe
Unrelated to that, it is hard for many people, including engineers, to visualize the magnitude of forces on a sheet pile wall. Once it is in place and excavation is well underway, it is best to Leave It Alone. I doubt if any of us would start arbitrarily cutting into a beam, or other structural member, that was known to be loaded, but the magnitude of the load was not known. Why do it with sheet pile?
Consider that sheet pile failure can be sudden, without warning and catastrophic... and the most likely time of failure would be while there will be workers inside the excavation making the cuts.
If ground water flowing through the gap in piling is a problem, you could sink a well point outside the gap to help.
Doing all this is a lot of trouble and expense, that's why it is not a "textbook" answer.
Just something to think about.
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RE: Braced Excavation with Crossing Utility Pipe
EIT
www.HowToEngineer.com
RE: Braced Excavation with Crossing Utility Pipe
www.SlideRuleEra.net
www.VacuumTubeEra.net
RE: Braced Excavation with Crossing Utility Pipe
Cheers!