INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

Under pinning of existing brick/stone walls

Under pinning of existing brick/stone walls

(OP)
Some old buildings have very wide stone or brick walls with no foundation or better said: the foundation = wall in the soil.
In many cases they are not deep enough.

I have some questions:

1. I usually see that only the half of the wall width is under pinned - is this OK? It doesnt look to stable in my opinion?! Wouldnt be better to do it under the whole width of the wall? Id like to hear some opinions/expriences (see attached file)
2. do you do under pinning from inner our outer side of the wall and WHY?
3. how to choose/calculate dowels for connecting old and new foundation?
4. is it possible to do under pinning on only one side of the building or not under every wall?

tnx for replies.

RE: Under pinning of existing brick/stone walls


1. I usually see that only the half of the wall width is under pinned - is this OK? I do not recommend underpinning half the width of a foundation. You need to check the required bearing area for the underpinning. If you underpin down to soil with the same bearing capacity, you need the same bearing area.
2. do you do under pinning from inner our outer side of the wall and WHY? Underpinning is usually done from outside the building. This makes it easier to remove the excavation spoils and deliver concrete.
3. how to choose/calculate dowels for connecting old and new foundation? Dowels are not usually needed. I would not underpin as shown in your attachment.
4. is it possible to do under pinning on only one side of the building or not under every wall? Underpinning is usually done only on the wall that abuts the excavation.

Check my web site for a presentation on the causes of recent building collapses in Philadelphia. The presentations describes typical underpinning.

www.PeirceEngineering.com

RE: Under pinning of existing brick/stone walls

PEinc, very good input. You guys (and gals) in NYC must have some big ones, if you know what I mean. I don't think I'd sleep (or go to the bathroom) until the underpinning was unnecessary and removed.

RE: Under pinning of existing brick/stone walls

I've seen some very poorly constructed old walls, with one the exterior wall of a prison. I suspect the guys that built it figured on some day removing stones and escaping. You could shove a folding ruler all the way through that wall. What I am getting at is, it may take injecting grout in the old wall before any underpinning is done to "glue" together.

RE: Under pinning of existing brick/stone walls

Excellent SEAoNY presentation, PEinc. Thanks for posting this.

...and great photo too, PEinc.

Appropriate that a CHAINSAW is used by the 'carpenters' on an underpinning project.

RE: Under pinning of existing brick/stone walls

The SEAoNY presentation is very good but I do not agree with everything in it.

www.PeirceEngineering.com

RE: Under pinning of existing brick/stone walls

Quote (PEinc)

but I do not agree with everything in it

From a technical perspective, or the roles/duties of those involved, other?

Interested in your comments.

RE: Under pinning of existing brick/stone walls

Ditto

RE: Under pinning of existing brick/stone walls

Technical - w/r/t steel wedges and jacking.

www.PeirceEngineering.com

RE: Under pinning of existing brick/stone walls

thanks PEInc

RE: Under pinning of existing brick/stone walls

Quote (PEinc)

Technical - w/r/t steel wedges and jacking.

So you don't recommend steel wedges, but do recommend hydraulic jacking, or do/don't recommend either?

RE: Under pinning of existing brick/stone walls

I have designed and built many, many underpinning projects. Wedging and jacking are rarely needed - as long as the underpinning piers are DRYPACKED properly.

www.PeirceEngineering.com

RE: Under pinning of existing brick/stone walls

Thank you, PEinc.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close