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Re: Foundation on Expansive Clay

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How about using continuous footing, if the pipes are
not too far apart and/or steel bracing between the
pipes to prevent differential movement.

Is 3' not too thick for a 7'x8' footing?

Alex C. Nacionales C.E.

--- Fountain Conner <fconner(--nospam--at)pcola.gulf.net> wrote:
> 
> I need to put some lightly-loaded foundations on
> clay "with the potential
> for expansion".
> 
> These foundations will carry a bark blowline in a
> paper mill.
> 
> If all were normal these foundations would be 7 feet
> long x 8 feet wide x 3
> feet thick.  They each would have a vertical pipe 20
> feet tall, carrying a
> horizontal blowline.  Maximum soil pressure (max
> load and wind) would be
> about 2000 psf.  Static maximum load is about 650
> psf.  The geotechnical
> report allows at least 2500 psf, plus 25 percent for
> short-term live load
> (like wind).
> 
> Plain vanilla...  Until I factor in the potentially
> expansive soil.  
> 
> My thinking is to turn down the outside edge of the
> footing an additional 6
> inches.  If this clay is expansive, it shouldn't be
> given to capillary
> action, and will provide a seal, preventing the soil
> beneath the foundation
> from seeing the varying moisture content.
> 
> What do you think?
> 
> Item 2:
> 
> I had intended to place each "mast" in a sleeve,
> plumb it and grout it
> into position -- cheap, but effective.  I *can* put
> a mast on a large,
> thick
> baseplate, and perch it on nuts below the base
> plate, with double nuts
> above.  If I do this, I can allow enough room below
> the lower nuts to
> adjust each mast plumb if there is some movement. 
> I'm hoping you guys can
> convince me that this step is overkill.
> 
> Ideas?
> 
> Thanx,
> 
> Fountain E. Conner, P.E.
> Gulf Breeze, Fl. 32561
>    Phone 850-932-5547
>    Fax      850-934-1916
> 
> 
> 
> 
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