Contact US

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.

Students Click Here

Weak Layer under mat foundations

Weak Layer under mat foundations

Weak Layer under mat foundations

Dear Friend,
I wonder if anybody has any openion on how to handle relatively thin weak layers encountered under the mat foundation in the shear wedge region. These type of layers are very weak (N<5) and compressible.
thanks a lot

RE: Weak Layer under mat foundations

The information you provide is very limited.  However, I will try to help, based on what you have provided.

Assess the load (and the resulting stress in the layer) and the tolerance of the structure to movement or to differential movement.  It may be that the movement caused to your structure, taking a worst case combination of properties for the weak stratum, is well within tolerance.

Given that your soil is compressible as well as "weak", and assuming that the settlement of your structure would be unacceptable, you either have to remove the material, replacing it with suitable material, or you have to treat the ground, or you have to pile the structure.  The most appropriate ground treatment will depend on the nature of the weak layer and on the overlying ground.

I have used "balanced foundations" before for large structures, but the compressible strata were not at shallow depth.

I suggest you obtain direct specialist advice.  If your structure is either populated or relatively large, the risk is too great for you to rely solely on advice obtained in this forum at a distance from your project.

RE: Weak Layer under mat foundations

Ditto Sean2's advice.

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! Already a Member? Login


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