Mike:
An engineer wouldn't break your bank, but I digress.
You don't say what the plan dimensions are of your 3.5' deep
hole are so it is hard to tell you anything but you could have
drilled and grouted some reinforcing bars vertical in a grid
pattern into the rock and utilized them as, rock nails, for a
lack of better term. This would have allowed you to build the
foundation shallower, but since you didn't ask earlier on here
I couldn't have given you the idea. I would be hard pressed to
give you exact pattern dimensions as I don't know what your
over-turning moment is.
Regards
Lonberg Design Group, Ltd.
Hank Lonberg, P.E.,S.E. / KR7X
President
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Michael
Goins
Sent: Friday, February 12, 2010 6:54 AM
To: towertalk
Subject: [TowerTalk] tower installation HG52SS
Guys, I'm needing some help here.
I am installing a HG52SS about 16 miles north of San Antonio
in an
area that is nearly all solid rock and I have two sets of
factory
specs on installation instructions from HyGain. One says (and
I'm
going from memory here, but I'm pretty sure I am correct)
30X30X42"
for the hole and the other says 42"X42"X5.5 feet for the hole.
The
issue is that under an inch or so of soil here it is virtually
all
solid rock. We are now down about 3 1/2 feet into solid rock
on all
four sides, and it has required a large jackhammer and many
hours to
get there. Assuming the base hole is to be designed for both
compressive and lateral movement, there is no way it is going
anywhere, either way.
This location is where I plan to live the remainder of my
life, so I
want it right. The tower will have a 2 el quad on it, and
likely
nothing every bigger than a 3 or maybe 4 el monobander as I
have never
owned a commercial antenna and have always built my own. With
it being
a crank-up, one antenna at a time (especially the 2 el quad)
is
sufficient for me.
My question is: Is this sufficient, considering the ground
materials?
I am highly considering the hole as is, wth a pad one to two
feet tall
around it above ground and tied into the factory rebar base
(which I
will have to cut down and slightly re-do in order to make it
fit the
current hole). With a sufficiently tied-in top pad, the tower
cannot
move in any direction as the above ground part would try to
push down
onto the rock around it, which it cannot do (as the rock 1"
and less
underground is solid).
An engineer is out of the questions as I am an average guy,
teaching
college for what often feels like minimum wage. I am also at
least 16
miles form the nearest possible engineer which would add to
the cost
factor.
Again, this is an amateur tower installation. The load will
never be a
lot as the tower is not rated for a lot of load. It cranks up
and
down, and I monitor the weather here, so it would be lowered
when
conditions suggested that it would be prudent.
I could sure use some opinions.
Michael Goins, k5wmg
Pipe Creek, Texas
Fast cars, slow boats, big dogs, and summers off to write
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.733 / Virus Database: 271.1.1/2682 - Release
Date: 02/11/10 08:09:00
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|