[TowerTalk] Tower base over ROCK (shale) experience??

[Joe Subich, W4TV]

On 10/13/2017 3:53 PM, bear wrote:

 > Hiring a soils engineer and PE is beyond the scope of the budget at
 > present.

You really need to bite that bullet.  Shales have a wide range of
strength and you need to know exactly both the compressive and
tensile strength of your particular shale.

> this stuff is a step down from bluestone, which is quarried not far
> from here... it will break down once broken up, and used as something
> like driveway fill, turning from large chunks back into granular
> soil in about 10 years, but as found in the ground it is stable.
That is true only so long as no forces are applied.  Both the tower
base (compression) and the guy anchors (tension) will apply forces
that are likely to cause the shale to fracture.

Bottom line, *don't guess*.  Get the soils engineer, pay for the
necessary load testing and have the base anchors designed properly
for the application.

73,

    ... Joe, W4TV


On 10/13/2017 3:53 PM, bear wrote:
> 
> 
> On 10/13/2017 3:33 PM, Grant Saviers wrote:
>> A little confusing to me what "solid shale" means.  If it really is 
>> shale (from what I know as shale in WPA, OH) then a carbide tipped 
>> drill will make quick work of drilling holes big enough and deep 
>> enough to hold a grouted or epoxied pin anchor for your guys. Several 
>> pins could be the sliding prevention anchors for the tower base. Then 
>> the question is how strong is your "solid shale". Shale is a 
>> complicated (anisotropic) rock and varies enormously site to site.
>>
>> This to me sounds that you really need a soils engineer and PE.
> Yes, this is exactly what I was speculating upon...
> 
> Hiring a soils engineer and PE is beyond the scope of the budget at 
> present.
> They seem to charge by the millisecond, sort of like attorneys and 
> doctors...
> 
> The question is how many holes, how deep and what diameter...
> 
> It's simpler and easier to do more than the minimum as far as the 
> install vs. hiring a PE, i would expect.
> 
> Also, in this area a PE approval is not required. Not in the local code.
> 
> "Solid shale" as opposed to broken shale or shale filled soils... this 
> stuff is a step down
> from bluestone, which is quarried not far from here... it will break 
> down once broken up,
> and used as something like driveway fill, turning from large chunks back 
> into granular soil
> in about 10 years, but as found in the ground it is stable.
> 
>                              _-_-
>>
>> Grant KZ1W
>>
>> On 10/13/2017 9:42 AM, bear wrote: 
> 
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