Probe rod references? Anyone?
Probe rod references? Anyone?
(OP)
I am just curious about documentation for a metal probe rod that I ususally use for near-surface stabiliby of a native cut. I know the concept is based on square area- the weight of my body on a very small area (the tip of the rod) will simulate a much larger weight over a larger area (like a building). I've had engineers in the past mention limitations to using the rod, as when there are larger rocks present. Does anyone know any papers or research that has been done on this? I know it all seems obvious, but it would be nice to know if there were any 'ground rules' one could follow, and cite, if possible. Thanks!





RE: Probe rod references? Anyone?
From: National Research Council Canada "Guide to the Field Description of Soils for Engineering Purposes", Technical Memorandum 37 (1955) -
" . . . it is difficult to drive a 2- by 2-inch wooden picket into dense soil for more than a few inches. A 2- by 2-inch picket can be easily driven into loose soils. If the grains are "cemented" together, density cannot be estimated by this simple method."
This is along the lines of chewing silt, etc. but it is a reference. Canada was at the forefront of geotechnical research back in the 50s and 60s.
RE: Probe rod references? Anyone?
RE: Probe rod references? Anyone?
If your cone is higher end like the Geo Cone with encased needle that just measures end bearing and side resistance is not measured, then I have always divided 4 by the cone readings of Kg/sq.cm to get my allowable bearing for 1" settlement. I have compared that with Allowable bearing based on N blows/ft and had identical parameters. I have used such cone on over 2000 lightly loaded structures founded on older alluvium and glacial tills with no problems. The factor of 4 is my way of converting the dynamic reading to static allowable bearing pressure.
If your cone is the dynamic cone with a falling weight at a small distance, then I believe Dr. Sowers had a paper on that since he designed it.
RE: Probe rod references? Anyone?
RE: Probe rod references? Anyone?
RE: Probe rod references? Anyone?
A good guide, but dense and sometimes difficult reading, for cone penetrometer is "Guidelines for Cone Penetration Test Performance and Design" by US Dept of Transportation Publication FHWA-TS-78-209.
We use the Durham Geo Static Cone Penetrometer model S-214 for some types of soil testing, correlate to compaction sometimes in hard to reach places. Their operating manual can be downloaded at:
http://www
RE: Probe rod references? Anyone?
RE: Probe rod references? Anyone?
35-45 95% compaction per ASTM D1557
45-50 98%
50+ 100%
Rocks will mess up the readings.