Structural section with high ground water 2

[earle]

I have a client wanting to develop industrial storage on a site with groundwater less than 1.5' below the surface. Soils are sandy loam, AASHTO class A-4. Where do I find guidance on a minimum surfacing structural section?

 

[fattdad]

Not enough information to provide a helpful answer. What is the soil profile? Is it sand and gravel or peat? Also, is the water perched or seasonally high?

If you are dealing with a largly loaded area, adding a few feet of fill will do little to mitigate the potential for a large areal load. It may provide improve the near-surface strength to help with the industrial slab design but the loading of the industrial floor. The "set of settlement" is what is critical for this design.

Provide some additional information and I'd be glad to further assist.

f-d

¡papá gordo ain’t no madre flaca!

 

[earle]

Sorry for the skimpy info, I was in a hurry.

The site will be used for pipe storage, with alleyways for equipment access, and bunks for pipe to be stored on. The bunks will probably be railroad ties, to raise the pipe above ground enough for the forklifts to stack and retrieve it. It will not be large uniform loads, and it will be open storage, not covered.

Groundwater is seasonally high. Soil section is sandy loam to about 12", fine sand to 24"±, and what looks like muck below. The client wanted to lay fabric and about 8" of 3.5" minus rock.

Is that enough info to start with?

E

 

[dicksewerrat]

Probably not good enough. Use a 'Geoweb" sandwiched betwtten a 6" lifit of your 3.5" minus and 6 inches of 3.5 minus. then put down 3 inches of recycled concrete crushed to 1.5 minus. Roll each layer with a proff roller weighted to 60,000 pounds

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[fattdad]

If you are dealing with outdoor storage and there is little consequence of settlement (beyond what you could mitigate by importing a few more loads of aggregate), I'd just remove topsoil and if it proofrolls under a fully-loaded 10t dump truck place my aggregate. I'm not sure you need the geotextile/geogrid if the subgrade proofrolls.

On the other hand, if the subgrade doesn't proofroll, you may want to use a geotextile. I'd consider a woven geotextile (e.g., Mirafi 500x) and then place a minimum 12 in subbase.

Just out of curiousity; how much slope is there on this site? If there is no slope, infiltrating rainwater will just fully soak into the open-graded aggregate. Not sure how rapidly the water will soak into the sandy loam layer (I could guess, but then again. . . ) but if there is construction traffic on a saturated subgrade, you'll loose strength. If you can't provide internal drainage to the subbase, I'd use the geotextile whether you pass a proofroll or not.

Good luck.

f-d, c.p.g., p.e.

¡papá gordo ain’t no madre flaca!

 

[earle]

Thanks, f-d and Richard. Fyi, the site slopes less than half a percent. I am concerned that the subgrade will probably saturate, since winters are pretty rainy here. I will spec the geotextile for sure. Thanks again.
E