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

Underpinning in Sand

Underpinning in Sand

(OP)
I am needing to carry out some underpinning to a dry pack sandstone foundation wall as I need to drop the floor level in a basement, however the footings are founded at a higher level than the proposed slab level.

I cannot use the conventional mass pour method of underpinning (which involves excavating alternate sections in sequence to a pre-established depth below the footing and place concrete on each pit; then repeat the method until the entire affected area has been underpinned)as I am in sand and the sand will not be stable enough to allow for the segmental excavation.

Is there any way to underpin this wall safely or do I need to support the entire upper structure using needles and pins, then demolish the existing foundation wall and rebuild the footing and wall at the appropriate level?

RE: Underpinning in Sand

HD69:
Get a GeoTech guy involved to confirm the sand conditions and that this would work in your case. Open up the existing lower slab and excavate down to the bottom of the existing footing. You may want to leave some slab (or blocking to the slab) in place to provide some lateral support for the existing found. Then use a pressure grouting system to solidify the loose sand under and for some distance behind the existing footing. You want to end up with something akin to a soft sandstone, so you can work and excavate it to do the rest of your found. work.

RE: Underpinning in Sand

(OP)
thank you dhengr

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