[TowerTalk] tower installation HG52SS / options

[Ivan Shapiro (KB1STH)]

My QTH/property is on rock.  In fact in many places the rock protrudes above
the grass.
We put up a 120 foot free-standing tower for a Jacobs wind turbine 11 years
ago.
After getting down as deep as we could with a big backhoe I had a company
come in with their rock-boring machine.
We had three cylindrical holes drilled.  Each one is 18 inches in diameter
by eight feet deep.
Filled this with rebar first.
Tied the rebar to the rebar cage inside the forms.  Forms were four feet
high, with about 2 feet protruding below grade.
Forms were nineteen feet on a side.  We poured around 27 or 28 cubic yards
of concrete.  Of course we insured that the anchors and first 20 feet of the
tower were plumb".

I never wanted to have to do any repairs to the base, and I think we have
achieved that goal.
Just wondering, however, whether you think this was way too much overkill.
Thanks
Ivan
KB1STH

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Jim Thomson
Sent: Saturday, February 13, 2010 10:41 PM
To: towertalk at contesting.com
Subject: [TowerTalk] tower installation HG52SS / options

gents

When installing free standing towers on ROCK,  you have a few options.   My
buddy has a huge trylon,  that is located on solid rock.
Instead of messing about  with jack hammers,  he used TRYLON'S    suggested
method and used  rock anchor bolts.

Three  holes were drilled into the rock,  about  2"  diam  x  XXX feet deep.
Anchor's inserted and packed  with special epoxy goop
[ NON shrinkable epoxy]   On some trylon towers,   2 x  anchor rods  are
used for each tower leg  [  6 x anchor's in total.. and 5' long] 

We also used the same technique at the Telco I worked at for 34 yrs...  for
microwave tower's and also cell towers... located on remote
mountain tops [ read  100++ mph winds + 1-3"  of radial ice]    Rock anchors
also used [ usually in pair's]   for guy anchors, for guyed microwave
tower's. 

Plan B  [ also from Trylon]   is  to use huge  jumbo size  HILTI  anchors.
These  things  are  are  24"  long  x 2"  diam ... and made  spec
for anchoring towers !     I have installed thousands of hilti anchor's  at
work, yr ago.. and usually in both floors and also hundreds of em
in the concrete  ceiling's  [+ elevator shafts etc]    We  hung  thousands
of lbs of cable  runways  on small hilti anchors, suspended from the
ceilings. 

These day's  everything has to be seismic rated in BC.  In the last few
years, all our  equipment bays [19"-30" wide] are heavy duty steel
with these monster size  hilti's  in the floor.    When that earthquake in
wash state hit us.. a few yrs ago.... they held just fine... didn't budge.  

Didn't even know they made these  super  jumbo size ones for tower's.   The
internal bolts  for em are  1" diam  x 30"  long.  The anchor itself
is  2"  diam   x 24"  long... and requires a special  hilti  drill.    These
2"  x 24" long hilti's  I believe, are made for CONCRETE... dunno if they
can also be used in
rock..or not.     The idea of em is so an  existing concrete  base can  be
re-used  on another tower.  All this info is on Trylon's  site.. or just
phone em. 

later....... Jim   VE7RF   
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