Kelly:
Digging this kind of excavation is a royal PITA. First, you dig the hole
the size of the bottom pad, e.g., 5X5 feet, to the final depth of the hole.
You place rebar for the pad AND for the pier. Then you pour only the bottom
pad concrete and let it set for a day. The next day you form up the pier and
pour it.
After this entire block cures for another day or two, you can remove the
forms. Now comes the fun part.
You'll have to back fill the hole around the pier. This means you must
place some earth into the hole around the sides of the pier, covering the pad
in the process. THEN you must ensure that the replaced earth is as compacted
as undisturbed soil by pounding on it with, for example, a 4X4 or 2X4 piece of
wood. Once that layer of soil (abt 6 inches or so) has been compacted, then
you add another layer of earth and repeat the pounding (compaction) process
until you reach grade. One might have a tendency to slack off a bit on
compacting the upper levels of earth due to fatigue. This won't give you the
mechanical performance from the earth that your tower will need.
I used the Trylon foundation design, that is, a monolithic concrete pour,
but with an undercut at the bottom of the hole. I did this by having the
backhoe dig the basic hole (5.5 X 5.5 feet six feet deep) and then shoring up
the sides. I then went INTO the hole (ever look up from the bottom of a narrow
hole in the earth?) and hand-dug the undercut. The backhoe bucket was small
enough that it was in the hole with me, but I had very little room to maneuver.
Thinking a bit about this compacting, if you decide to go the way of the
two-pour pad and pier design, you might want to really overdig the hole and use
a gasoline powered rented compactor to do the job with less human effort (and
fatigue.) It'll sure beat using a two-b'-four!
GL es 73 de
Gene Smar AD3F
> This wasn't exactly what I was looking for. The Super Titan towers
> and the AN Wireless Towers show foundation plans where the bottom of
> the hole (the foundation) is wider than the rest of the hole (the
> pier). The foundation at the bottom is significantly wider (like
> 18"). How do people dig these types of holes?
>
> On 7/5/05, Rick Scott <rickn7hj@gmail.com> wrote:
> > http://www.windturbine.net/files/Misc%20Data/anchor%20system.doc
> >
> > 1.4.4.1
> >
> > Figure 1.4 shows the diagram.
> >
> >
> > Scotty N7HJ
> >
> > On 7/5/05, Kelly Johnson <n6kj.kelly@gmail.com> wrote:
> > > Can someone explain to me how a Pad & Pier Tower Foundation hole is
> > > dug? I had never seen a Pad & Pier Foundation Spec until this weekend
> > > and after seeing it I couldn't help but wonder how you would dig such
> > > a hole.
> > > _______________________________________________
> > >
> > > See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
> questions and ask for Sherman, W2FLA.
> > >
> > > _______________________________________________
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> > > TowerTalk@contesting.com
> > > http://lists.contesting.com/mailman/listinfo/towertalk
> > >
> >
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather
> Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
> and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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