Sampling spoon on guide rail post pounder?

[ACtrafficengr]

Has anyone seen a way to retrofit a guide rail post driver to take soil samples? I'd like to be able to take subbase samples to help determine causes of pavement distress. We already have the post driver, so I was thinking that should be able to push a spoon a foot or two into the subbase. Any ideas?

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

 

[Ron]

Don't see why it couldn't work. The blow counts won't mean anything unless you do enough and in different materials to establish a correlation to "N".

I assume you can weld or otherwise fasten a short piece of drill rod to the bottom of the driver, to which you can screw the 18" or 24" spoon.

 

[TDAA]

What sort of testing did you want to do to the samples? Are you looking for a California type sample in a brass tube, a Split Spoon sample, or a Shelby type sample.

There are a few ways of getting what you want, but it depends on what you need to run.

 

[ACtrafficengr]

In the context of a "3R" (Resurfacing, Restoration And Rehabilitation) highway project, we want to find out whether the subbase is clean, or if we need to some sort of full depth stabilized reclamation or reconstruction to correct it. AADTS are usually under 1500.

So, we want to go down about a foot and sample the granular subbase, so that we can do some basic tests for gradation, plasticity, etc. I suspect that if we have to look at the subgrade, we probably need to contract out for a geotech, anyway.

We have a blacksmith/welder (yes, that's his job title) in the vehicle repair shop, so we can do some fabrication in-house.


"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

 

[BigH]

Ever think of test pits - can see the material "in bulk" and could, if you wanted perform a sand cone for density check (and you can use the material dug out for a gradation). As you indicated, you are only going down a foot or so.

 

[dirtydude]

Test pits is what immediately came to mind for me. It would even be a cheaper operation overall IMO.

 

[Ron]

Test pits (or observation pits as the attorneys want us to use) are great, but for evaluation of existing pavements, you have to be able to evaluate the pavement with as little intrusion and traffic interruption as possible. This is done with small penetrations of the pavement with the intent of gaining as much information as possible within the small penetration.

The idea of a dynamic penetration and sampling deserves merit. One significant problem is that the material gradation of the base material might easily exceed the size of the split spoon...in fact, it almost always does so.

Perhaps a variation of the extremes between a "test" pit and a single penetration hole is the answer.

 

[BigH]

In high traffic areas in India, we did the test pits in the shoulder and say 1 m out into the pavement. Didn't disrupt traffic too much. You could always do them on a night shift - with proper safety and this would have even less impact. Agree that one would want to be "less disruptive" to traffic but a few hours of disruption to get a "good" road on rehab . . .