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Re: Drilled pier foundation

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Rajendran,

Auger cast piles can be competitive especially if you have a lot of piles.
Here are some of the advantages:

1.  Very fast.  We have two rigs and they can install 30 to 40 piles per
day (+/- 70 feet deep).

2.  They can penetrate very stiff as well as very loose layers which we
have both of on our job site.

3.  Their tolerance's for horizontal and vertical seem to be very good.

4.  Water table is not a problem.

Casing is not required.  They  use a hollow stem auger to drill the hole,
then when they reach the bottom they pump grout through the center as they
pull out the auger.  Since this is under pressure it seals the loose areas
and forces out/seals water if in ground water.  By the way, our contractor
is Berkel and Company Contractors Inc.

Thomas Hunt, S.E.
Duke/Fluor Daniel

----- Forwarded by Tom Hunt/DFD on 03/06/01 04:18 PM -----
                                                                                                                   
                    Padmanabhan                                                                                    
                    Rajendran            To:     seaint(--nospam--at)seaint.org                                                 
                    <rakamaka@yah        cc:                                                                       
                    oo.com>              Subject:     Re: Drilled pier foundation                                  
                                                                                                                   
                    03/06/01                                                                                       
                    03:02 PM                                                                                       
                    Please                                                                                         
                    respond to                                                                                     
                    seaint                                                                                         
                                                                                                                   
                                                                                                                   




Thank, Tom, for the information.

Since Auger cast pile is a speciality, it is,
presumably, more expensive than standard drilled pier.
So, what is the advantage of auger cast pile? Is it
used in silt/sandy stratum with high water table? Does
it require the use of a casing?

Rajendran

--- Tom.Hunt(--nospam--at)d-fd.com wrote:
> Rajendran,
>
> For typical drilled piers (+/- 2 to 3 ft diam.) the
> rebar is normally
> installed prior to placing concrete.  However, for
> auger cast piles the
> standard procedure is to drill down to pile length,
> then pressure grout
> through the stem as the stem is removed, and then
> the rebar is pushed into
> the hole after the drill is removed.  We are using
> this procedure on a
> current project with 16 and 24 inch piles.  The
> rebar cages are
> approximately 30 feet long.  Note that auger cast
> piles are a real
> speciality and require a very experienced
> contractor.  They also use a
> special grout mix that is very fluid to allow the
> rebar to be pushed in yet
> achieves 4000 psi or better at 28 days.
>
> Thomas Hunt, S.E.
> Duke/Flour Daniel
>
> ----- Forwarded by Tom Hunt/DFD on 03/06/01 02:01 PM
> -----
>
>
>
>                     Padmanabhan
>
>
>                     Rajendran            To:
> seaint(--nospam--at)seaint.org
>
>                     <rakamaka@yah        cc:
>
>
>                     oo.com>              Subject:
>  Drilled pier foundation
>
>
>
>
>                     03/06/01
>
>
>                     12:41 PM
>
>
>                     Please
>
>
>                     respond to
>
>
>                     seaint
>
>
>
>
> Drilled pier foundations have reinforcement
> (vertical
> bars + ties or spirals) in the upper few feet of the
> piers. Recently, I heard that it is common for the
> construction folks to place the pier concrete and
> then
> push a preassembled cage of reinforcement through
> the
> concrete. Does this method guarantee that the rebar
> can be placed reasonably close to the way it is
> detailed on the drawing? Is'nt there a good chance
> that the rebar may be bent and mangled?
>
> Rajendran
>
>