×
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!
  • Students Click Here

*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

Jobs

7 feet of soft soil

7 feet of soft soil

7 feet of soft soil

(OP)
A 500 foot long by 50 foot wide area has approx 7 feet deep soft saturated fat clay.  It is set to receive 13 ft of fill and hold up some small structures and possibly a parking lot. Our preliminary recommendation is to over excavate and replace the 7 feet of soft material.  Any other cost effective ideas?

Thanks

kansascity

RE: 7 feet of soft soil

6500 cubic yards to remove and replace seems a rather modest cost element even at $7/yd, (91,000 dollars for half acre site).  Dirt is cheap compared to repair of foundation failure!

RE: 7 feet of soft soil

With 13' of fill, will the clay even be a factor?.  That is deep enought that the moisture content may not vary too much.  I would think that it would depend on the foundation loads and estimated settlement.

RE: 7 feet of soft soil

With the limited info on what this loc. will be, structures being a very broad term, I would not undercut 7 ft.  ...... with a proposed 13 ft. fill. Some times the deeper you get the worse it gets....water etc.  

I am assuming your "soft matl." is a lower P.I. soils?  If the heavy fatty clay is a big worry, you could Lime treat it about a foot thick, then begin your fill.

I have seen 10+ ft. of fill bridge a multitude of bad stuff. Once you start your fill,I would not over compact or vibrate too much until at least a few feet of new material is in place ( you might pump up some moisture etc.)Shoving a 3-5 ft lift across this area initially might be the way to go before you begin to compacting.

Good Luck

RE: 7 feet of soft soil

Do you have time to surcharge the area with extra fill, and allow any settlement to take place prior to constructing the structures?  If it works, it's certainly less expensive than overexcavating.

RE: 7 feet of soft soil

Possibly geopiers

RE: 7 feet of soft soil

I see this is somwhat old at this point, but . . . Since no one else asked:  What is your concern?  Is it a constructability issue, or are you concerned about long term performance, such as consolidation issues? Both?

I assume the soft material is at/near the surface.  What is below? Where is ground water?  Is the material suitable for reuse? Can it be properly conditioned during the construction period?

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