Pocket penetrometer
Pocket penetrometer
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RE: Pocket penetrometer
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RE: Pocket penetrometer
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and its adapter foot should do the trick.
This does beg the question why use a dial penetrometer (600$) or a cone penetometer (1300$) or even a dual mass dynamic penetrometer (3000$)
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RE: Pocket penetrometer
RE: Pocket penetrometer
Instead get a cylindrical sample and test it for unconfined compression strength.
How?
Well take a tin can or similar metal cylinder (both ends open) and force it into your material to test, perhaps with some excavation around the sides to assist in the penetration. Ideally the undisturbed length should be twice the diameter.
Then take it home to your bathroom scale and slowly compress it. At a deflection of say 10 to 20 percent of the height, use that poundage to figure tons per square foot. It will be a rough figure, but probably more accurate than a penetrometer anyhow. Cost is zero.
For many tests, extrude the sample out on the job and wrap in plastic to maintain moisture. Oh yes, take the bathroom scale out there if the wife OK's it.
RE: Pocket penetrometer
I bought a penetrometer for a "one time use" and have used it many times over 20 years. It was cheaper than 20 years' worth of soup cans and, when using it, I look a little bit more professional than if I were to use a tin can and a bathroom scale.
www.PeirceEngineering.com
RE: Pocket penetrometer
When I first went on my own, without any test equipment, and not much money, I used a drill press and a bathroom scale for testing split spoon samples for Qu. It worked and later the more fancy stuff was not any more accurate.
I suppose out on a job where you need to create an impression that you are an expert, this tin can thing might not be so hot. Then again, real experts may criticize the pocket pen and ask for a more sophisticated test method as being more dependable. Depends on what the result is used for.
RE: Pocket penetrometer
The project engineer questioned my use of this non-ASTM testing method. I told him that, since he didn't do any borings in the river, my method gave better information than he had. I also told him that I had better information than if he did have borings. He backed off. The cofferdam was built and performed as intended. Sometimes you just gotta do what you gotta do - like your tin can experiment.
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RE: Pocket penetrometer
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RE: Pocket penetrometer
Thanks for everyone's help on this.
RE: Pocket penetrometer
RE: Pocket penetrometer
PEinc, I am wondering what is the base/theory for estimating the friction angle by this method. If the sample is below the river bed, it must be below the groundwater table anyway which means the in-situ condition is saturated. In this case, the weight of a clayey sample before and after flooding it should not change that much. In case of a sandy soil, it is a bit complicated as saturated sand may lose some water during sampling and extraction and then you get it back to saturation. In this case, the weight difference may mean something. However, it is complicated as you cannot say how much water the originally saturated sample may lose through the sampling process. On the other hand, I can understand if you let the sample dry first then measure the dry weight and then make it saturated, and measure the saturated weight. In this case, the weight difference for sandy soils provides a base for estimating the friction angle (may also applicable for clayey soil). I appreciate if you can help me to understand your method.
RE: Pocket penetrometer
www.PeirceEngineering.com
RE: Pocket penetrometer
RE: Pocket penetrometer
www.PeirceEngineering.com
RE: Pocket penetrometer
RE: Pocket penetrometer
If Engineers are going to provide a geotech or foundation report for a project, the report should have some useful information in it besides cut and paste geologic history. Is it too much to ask for some actual unit weights, phi angles, and cohesion?
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RE: Pocket penetrometer
www.PeirceEngineering.com
RE: Pocket penetrometer