In a message dated 4/22/01 2:08:32 PM Pacific Daylight Time, n4vi@arrl.net
writes:
> As my tower plans come together the odds are increasing that I will be
> installing a crank-up tower and the substantial base associated with it.
>
> Depending upon the final tower location, the odds are quite high that I
> will hit bedrock anywhere from just below the surface to 3 feet below
> the surface. Admittedly, I don't really know the definition of
> "bedrock" and if all bedrock is the same, but the main point is digging
> a hole will be much more difficult then in regular soil (whatever that
> it).
>
> I would prefer to dig a hole of correct dimensions and not use the
> "bedrock" as part of the tower support. This may or may not be
> realistic. I would like input from towertalkians in regards too:
>
> 1. Digging holes in extremely rocky soil (assume blasting is not
> allowed)
>
> 2. Methods of determining bedrock strength and attaching a tower base
> to bedrock.
>
Didn't see too much of a response on this so here's my take on your
questions.
In any case you need to get a PE (Professional Engineer) involved so that
you get the correct base for your conditions and requirements.
There are about 8 or 9 different types of "soil" and they all have
different holding capacities so it's pretty difficult to define what you've
really got. Shattered rock is one category which is common.
If you really do have bedrock, the PE can use the bedrock as part of the
base with drilled holes and epoxied anchor rods to bond the whole thing
together.
The only way to *really* find out what your soils conditions are is to
employ a geotechnical firm to do a soil study. They will dig several holes
and use their professional expertise and experience to give you the answers.
This ain't cheap. A few phone calls to companies in this kind of business or
local construction can probably give you some insights and answers without
spending the money.
Cheers & GL, Steve K7LXC
Tower Tech
List Sponsor: ChampionRadio.com - Trylon self-supporting towers,
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