Abandoning SOE soil tiebacks without de-tensioning

[LECT12]

Aside from it becoming "someone else's problem", are there any safety concerns with abandoning a tensioned soil tieback after your SOE is complete? OSHA safety and general worker safety comes to mind - you can't always control what the contractor does on site and all it takes is for one stupid mistake to become a fatal flaw.

 

[PEinc]

On many, many projects, temporary tiebacks are abandoned in place without detensioning. Over more than 40 years, I am unaware of this ever being a problem. Usually, the tiedback sheeting wall is built off-line of the new structure and the tiebacks are detensioned so that the contractor can salvage the steel tieback wales when backfilling the wall. However, for sheeting walls where the new structure is built up against the sheeting, there are no wales and the tiebacks cannot be detensioned - at least not without great expense.

http://www.PeirceEngineering.com

 

[LECT12]

Hi PEinc,

Thanks for the reply. In this case I'm the engineer working on behalf of the neighbor. My only concern is safety and additional costs incurred by my client to remove tiebacks in the future if/when they decide to develop their property. My worry is that future development will occur and the foundation contractor might not be aware that there are actively tensioned tiebacks in the ground which may result in change orders and/or damage to equipment due to presence of tiebacks. I know with proper construction procedures it is generally not an issue, but isn't this an additional burden/liability on the future developer?

P.S. - visited your website, and it's a really small world! Your office designed the underpinning on one of my jobs in Flushing!

 

[PEinc]

Backhoes can easily dig through a tensioned tieback anchors from a previous, adjacent project. The soil around the tieback confines the tendon and prevents it from flying around and injuring someone. Just removing the overburden soil from above a tieback anchor can cause creep and detensioning.
What Flushing job - Eastlake on Main Street? Nice job; tough GC to deal with. Soil nailing and tiedback underpinning.

http://www.PeirceEngineering.com

 

[LECT12]

Yes, that is the general consensus amongst the geotech engineers I have spoken with. I somewhat agree, but also think it's an additional "burden" on the client to deal with abandoned tensioned tiebacks. Anyway, it all boils down to the access agreement between neighbors.

Yes, Eastlake. The underpinning wasn't the worst part. We got kicked off the job (GC superseded us with their own engineer). Financing dried up after foundations were poured (no subcellar or cellar slabs were poured) and they had to backfill the site.... so their engineer allowed them to backfill behind the wall with no slab bracing (despite our drawings expressly telling them that is not allowed). Their engineer got spooked and basically fled the country after the job was done. Heh.

 

[PEinc]

You had it worse than I did. Sorry.

http://www.PeirceEngineering.com