[TowerTalk] Soil testing

[Jim Lux]

At 12:59 PM 3/29/2006, Ronald, Douglas S wrote:
>Tower talkers,
>
>Before I hire a soils engineer and drag him out to a remote location, I
>was wondering if there were some subjective tests I could do on my own
>to ascertain my soil strength.
>
>I'm putting up an 80' tower with 4 guys all of which need reinforced
>concrete foundations. I plan on contracting with a local bulldozer owner
>to flatten an area of 230' x 115' +- 3 inches with compaction to 95% in
>the fill areas. Since I probably won't be there when the work is done, I
>would like to check the quality of the compaction. The antenna uses 4000
>PSI soil for its specifications. I am hoping there is a probe or
>something I could pound into the prospective areas to see if the
>compaction is even close to the 4000 spec.

You might want to look at this for ideas:
http://geotech.uta.edu/lab/Main/Soil%20Lab/09_UCS/UCS.pdf

here's some data from CalTrans on field testing of soil for trenching and 
shoring:
http://www.dot.ca.gov/hq/esc/construction/Manuals/TrenchingandShoring/appendix_B.pdf

In particular, you might want to look at the cone penetration and standard 
penetration test.  The latter consists of driving a 1.4 inch ID, 2" OD 
sampler 18 inches into the bottom of a bore hole using a 140(?) hammer 
dropped 30 inches.  The number of blows required to drive the sampler the 
last 12 inches is the measurement.


Here's how they do the test in the lab:
http://www.dot.ca.gov/hq/esc/ctms/ctmsindex200.html

Although many of the procedures just say: do the test in accordance with 
ASTM D xxx


http://www.dot.ca.gov/hq/esc/ctms/CT_221.pdf


>All I know about the soil from looking at it, plus when a well was
>drilled, was 2 to 3 inches of top soil above several tens of feet of
>chert.
>There are outcroppings of bedrock which I have seen a D9 with a ripper,
>turn to gravel on a neighbors parcel.
>
>This has probably been discussed before, but I didn't find much in the
>archives other than some screw anchor questions.
>
>Thanks in advance,
>Doug Ronald AE6SY
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