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.
Lonberg Design Group, Ltd.
Hank Lonberg, P.E.,S.E. / KR7X
[mailto:firstname.lastname@example.org] On Behalf Of Michael
Sent: Friday, February 12, 2010 6:54 AM
Subject: [TowerTalk] tower installation HG52SS
Guys, I'm needing some help here.
I am installing a HG52SS about 16 miles north of San Antonio
area that is nearly all solid rock and I have two sets of
specs on installation instructions from HyGain. One says (and
going from memory here, but I'm pretty sure I am correct)
for the hole and the other says 42"X42"X5.5 feet for the hole.
issue is that under an inch or so of soil here it is virtually
solid rock. We are now down about 3 1/2 feet into solid rock
four sides, and it has required a large jackhammer and many
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
nothing every bigger than a 3 or maybe 4 el monobander as I
owned a commercial antenna and have always built my own. With
a crank-up, one antenna at a time (especially the 2 el quad)
sufficient for me.
My question is: Is this sufficient, considering the ground
I am highly considering the hole as is, wth a pad one to two
around it above ground and tied into the factory rebar base
will have to cut down and slightly re-do in order to make it
current hole). With a sufficiently tied-in top pad, the tower
move in any direction as the above ground part would try to
onto the rock around it, which it cannot do (as the rock 1"
underground is solid).
An engineer is out of the questions as I am an average guy,
college for what often feels like minimum wage. I am also at
miles form the nearest possible engineer which would add to
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
down, and I monitor the weather here, so it would be lowered
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
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