[TowerTalk] ROHN tower anchor question

[Pete Smith]

At 09:09 AM 7/30/00 -0400, Jim Idelson wrote:
>
>While I cannot give any further numerical insight into how the soil
contributes 
>to the effectiveness of the anchor, I do recall one practical piece of 
>information that my PE gave me when we designed my installation. He made it 
>clear that undisturbed soil retains significantly more strength than soil
that 
>has been excavated and replaced during the construction process. For this 
>reason, he strongly recommended hand-digging base and anchor holes,
instead of 
>using a backhoe or other excavation machine. He felt that the end result
would 
>be significantly stronger if the holes were dug to exact spec by hand.

I'm confused.  There's no way you can pour a concrete anchor without
disturbing the dirt above it, because you have to fill after pouring.  Was
he talking about the soil around the anchor, including (I guess) the
portion that is in the pull axis but outside the hole itself?  Similarly,
as far as the base block is concermed, was his objection to the backhoe the
idea that one or more sides of the hole would be somewhat cut out?

It's hard for me to picture that Trylon and other manufacturers of
self-supporting towers with multi-yard bases really expect the installer to
dig the hole by hand.  Maybe their specs already have soil disturbance
accounted for(?).


73, Pete Smith N4ZR

The World Contest Station Database 
is back up and running at
http://www.qsl.net/n4zr 



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