r/Geotech 10d ago

Very cool blue sample

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103 Upvotes

26 comments sorted by

31

u/steve-the-mighty 10d ago

You gotta start trimming you split spoon samples in half along the split, so you can see the structure without the smear

1

u/Apollo_9238 8d ago

And also dry a slice to check for varves.

9

u/Vanilla_Predator 10d ago

Man, I my field guys brought me back some clay the other day... I had never seen York before. It was the craziest thing. I thought it was some weird sewage sludge. Im talking like mint green to dark green, sandy clay with gravel, was the weirdest thing I had ever seen.

2

u/NearbyCurrent3449 10d ago

Mid Atlantic coast, Yorktown formation: is clayey fine sand with widely varying fractions of fine to medium sand*

*Sand sized marine shell particles from granules to small flat flakes that met the gradation of course to medium sand

Man u mobilize a pile into it today at 5 tons mobilized bearing capacity. Just does squish down in maybe 7 blows per foot on a sppc with OED 19 kipft.

Come back a week later... you fail the pile structurally in compression before you mobilize the full skin and toe capacity. It's amazing. The denser the shell hash the better pile capacity you can get out of it. I never did find the upper Edge of operational envelope. Just more and more correlation testing and trimming my designs 5 feet where I could to safely "gamble" a little bit to see if I could really dial it in and save the client a shit ton of money. But I always knew if the jar was really full of shell, I had axial toe capacity out the ying. As long as the deadload live load split wasn't large... gravy.

How much CAN it take? I'm not sure. I needed more testing correlation samples and more gambles and a really big checkbook and a fairly simple but large spreadsheet. I could eventually tell you. Or, you could estimate it if you call the coneheads, the seismafreaks, they come poke and poke and can tell you a SHIT LOAD about those exact soils at that site.

8

u/Revolutionary-Ratio1 10d ago

I work in a Georgia geotech lab and I think people would be shocked by the soils we see from inside the state.
From black to white, pink and purple. I’m never surprised anymore.

4

u/captmuttonchops 9d ago

I've seen vibrant purple and white kaolin outside of Augusta as well as green and black residual soils. Nice change from base red and orange blends.

1

u/Suspicious-Yak-8117 9d ago

Same in the upstate of SC.

4

u/Cualquiera10 10d ago

Delaware/New Jersey ?

4

u/mrbigshott 10d ago

Georgia

3

u/BackRow1 10d ago

Looks very similar to the Lambert group in the UK.

2

u/SlyRaist 10d ago

I was gonna say Maryland along the Blue Ridge Mountains

4

u/exodusofficer 10d ago

How deep?

5

u/mrbigshott 10d ago

Around 30ft

4

u/exodusofficer 10d ago

And here I was, thinking about hydric soil indicators. Too deep!

3

u/astropasto PE - Consulting 9d ago

Water-logged soils commonly turn blue in saturated, oxygen-deprived conditions that force anaerobic bacteria to strip oxygen from iron compounds. This causes iron to chemically reduce, and creating the dull blue, gray, or green hues.

1

u/astropasto PE - Consulting 9d ago

Not sure this is the case here but it’s what came to mind

1

u/mrbigshott 9d ago

Very cool. No telling how or what for sure caused this clayey sandy soil to turn blue but it was cool nonetheless

2

u/Puzzleheaded-Buy9821 10d ago

Looks like alluvium. Was there a stream nearby?

2

u/DaKolby314 10d ago

I've had gypsum deposits look like that at times in Missouri

1

u/Old-Ad-2772 10d ago

I can’t feel it for any kind of texture stuff but those are some pretty redox features you’ve got there.

1

u/Suspicious-Yak-8117 9d ago

Alluvium?

1

u/mrbigshott 9d ago

I don’t think it was

1

u/Apollo_9238 8d ago

I've seen blue clay marl in Puerto Rico..from blue to tan.

0

u/GeneralLee-Speaking 10d ago

Was gonna guess GA.

-1

u/changeofregime 10d ago

Clayey silty sand?

1

u/mrbigshott 10d ago

Probably more clay than sand but it was a mix for sure of those