×
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

Tank Loading on Fill and Preconsolidated Peat

Tank Loading on Fill and Preconsolidated Peat

Tank Loading on Fill and Preconsolidated Peat

(OP)
Scenario: A 4.3 m diameter and 3 m high tank is to be founded on the following soil profile: 4.5 m of sand fill (N=16), 1.5 m of silty clay fill (remolded till N=10), 1.1 m of peat (N=8), 4 m silty clay (N=5), and silty clay till below. The fill has been in place for ~15 to 20 years with an unknown history.  The boreholes indicated "clean fill" with essentially no deleterious materials.

Questions: 1)For a shallow foundation (i.e., gravel pad or concrete slab), how much additional settlement could be expected from the peat layer? 2)What would be an appropriate Es value to use in determining elastic settlement?

RE: Tank Loading on Fill and Preconsolidated Peat

Tank is for what material?  Oil, water, ???  N values seem high in the peat - but then again it is overlain by some 100 kPa pressure - assuming that the groundwater level is at the top of the peat - another question - where is the gwl?  

Not a high tank - even full of water only some 60 kPa bearing pressure including slab and tank dead load - not much.  I think that I would use a square of strip footings or a ring footing properly spaced so as not to overlap or create large moments on a supported slab then put the tank on it.  The footings in N=16 sand fill would likely be some 600 to 800 mm in width.  Depth of influence of the footings would be, say, 3x800 or 2.4 m (+ 400 or so for frost although it would be argued that clean sand fill is non-frost susceptible) - which means that the pressure bulb of interest is inside your fill - so tank pressure wouldn't be seen by the peat.  I'd not worry too much about immediate settlements based on this scenario - you should likely have less than 25mm or so.  If you think that the sand is not uniformly compacted, then dig out a metre or so and pack it.  May have continued secondary compression of the peat - but after 15 some odd years, you would be in a very long log cycle.
cheers

RE: Tank Loading on Fill and Preconsolidated Peat

(OP)
Thanks BigH!

The tank is for a cautic solution to treat acid water.  Also, the GWT is ~3.5 mbgs. Any other comments would be appreciated.

RE: Tank Loading on Fill and Preconsolidated Peat

mbgs? - oh, m below ground surface.  As I said, check out your frost depth. But besides what I alluded to earlier which is fine, you might want to put on a pad of good well graded sand and gravel, say 1 m thick on top or as a replacement of the sand fill.  Again, the size is quite small.  Different scenario if the tank had diameter of 10 m (more or little less).

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