×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Rising Groundwater and Foundation Settlement

Rising Groundwater and Foundation Settlement

Rising Groundwater and Foundation Settlement

(OP)
Could rising groundwater with occasional inches of ponded water contribute to settlement of a column footing?  I have encountered a footing where groundwater rises to within several feet and settlement has occured.  The footing bears on stiff to very stiff clay with sand.  A few inches of ponded water is also present sometimes near the footing.
I understand that the soil stresses will decrease with rising groundwater, but would this cause settlement?

RE: Rising Groundwater and Foundation Settlement

I do believe that saturation of soils affects the bearing capacity of soils and also the stiffness.

RE: Rising Groundwater and Foundation Settlement

In theory, the ultimate bearing capacity of the footing will be reduced by a rise in the water table.  It would be logical to assume that this could mean some settlement could occur (due to a rise in the water table) since the ratio of applied pressure to ultimate resistance has been increased (factor of safety reduced).  I have not seen this occur in Florida; however, most of the time our water tables are located near the ground surface anyway. I suggest you monitor settlement of this footing for a period of time to see if the settlement is load-related or due to groundwater issues.

RE: Rising Groundwater and Foundation Settlement

First I would check the load on the column and determine the bearing value.  Just to see that the problem isn't due to overloading.

When clays become saturated, the shear strength of the soil is diminished, and hence the bearing capacity.

Often, most clay soils are saturated all the time (even in very dry years), except for the top few inches that dry out.  This is because the fine grain size promotes capillary rise and it wicks moisture from other places.  In non-fissured clay, this rise can be several feet.  Also because of the fineness, the rate that water flows through clay (percolation rate) can be very low so little is lost to evapo-transpiration.

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



News


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