Undisturbed samples
Undisturbed samples
(OP)
Hi,
Is any good way to take undisturbed samples for cohesionless type soils? For example, SM soils for triaxial or unconfined compression tests.
Thanks for your help.
Is any good way to take undisturbed samples for cohesionless type soils? For example, SM soils for triaxial or unconfined compression tests.
Thanks for your help.





RE: Undisturbed samples
RE: Undisturbed samples
RE: Undisturbed samples
RE: Undisturbed samples
RE: Undisturbed samples
RE: Undisturbed samples
This also works for weak stuff, such as waste bark or flyash, but much lighter loadings and load measuring equipment.
RE: Undisturbed samples
RE: Undisturbed samples
Sorry, but the equipment is gone, some even scrapped as I moved from plenty of room country lot with shop to a city lot and standard house. One item of importance is with real strong ground, you need a pretty hefty normal load. So I made a proving ring from the outer race of a very large ball bearing that came from the junk box of a large construction equipment shop. It was roughly 8" OD with the "band" being about 2.5" x 3/4". A dial gage is fitted inside. The thing was calibrated in a compression testing machine. The loading was applied vertically through a screw jack, but a hydraulic jack cam be used. The box was made from steel angles with galvanized 3" legs, salvaged from a scrapped windmill. Also the horizontal strain was measured with dial gases suitable for 2" throw. You can buy kits for the horizontal loading hydraulic cylinder in either 10 or 20 ton capacity. Item 15616 at Northern Tool (Porta Power). Add a pressure gage and calibrate it in the testing machine also. In an excavation that pushes against a steel plate or plank against the nearby earth. You gather from this that I was a guy that made a lot of his own test gear. At 87 now, it's tough not to even have a welder here for simple fixes.
If you try to jack against a vehicle on rubber tires, it takes a lot of jack "throw" to get the vehicle up off the tires. I learned the hard way once with two scrapers back to back as the vertical reaction. The back-hoe bucket resting on a support (so it does not move) works great. Hopefully the operator does not fall asleep while you make use of his machine.
RE: Undisturbed samples
Unless you are able to arrange a field contraption like OG's, or to freeze the soil (a very expensive and Tricky practice, as thawing it properly is also critical), the only way is as per BigH's suggestions, to reconstitute the sample. As far as I know, the comparisons between reconstituted sample and undisturbed samples (with frozen sands I believe) are pretty encouraging.
www.mccoy.it
RE: Undisturbed samples
RE: Undisturbed samples
RE: Undisturbed samples
RE: Undisturbed samples
RE: Undisturbed samples
I like your story--- We must be about the same age--I've been in this field since 1976. Improvised a lot of stuff. It was fun---now, not so much---time to move on.
RE: Undisturbed samples
RE: Undisturbed samples
RE: Undisturbed samples
RE: Undisturbed samples
You seem to have maintained a good attitude---better than i can say of myself. I am increasingly frustrated by young ( fresh out of college guys and gals) who want to impress the boss that they can do it faster, and cheaper, yet don't know anything about the testing we do, or why it is important. One recent example--I was doing roofing inspections on a shopping center addition. The roofers were working from column line F to L, but could go no further because the structural inspector had not inspected past line L, and there was, in fact, no decking beyond line M. The young guy knew he got a BONUS when the roof was installed to line P, and was demanding that the roofers meet his deadline. I asked if he wanted them to roll out the roofing and then slide the decking under it. He didn't understand....
Its time for me to at leaset semi retire, if I can find someone who will let me work just 2 or 3 days a week. the workload where I am is such that I need to be here everyday.
RE: Undisturbed samples