Skin friction value of crushed gravel

[Polecat]

Does anyone have a feel of what the skin friction value of compacted crushed stone would be? The application would be placing a smooth concrete pole in an augered hole and backfilling with #57 stone. The backfill would be consolidated in layers using a long-stemmed vibrator. I'm trying to get a handle on estimating the installation's frictional resistance to the pole weight and vertical load.

http://www.spiraleng.com

 

[oldestguy]

I'd liken this to what values are commonly used for driven piles. They can range from a low value of 400 to perhaps as high as 800 psf, with a s.f. of 2. Is your pole tapered? How fussy are you if you get some settlement?

However, your resistnace also depends end area and soil bearing there, as well as the diameter of the hole dug and its side condition. Then the shearing resistance of gravel to soil interface may be critical.

Another factor is lateral overturning loading of the pole and the ground resistance for that effect. It may control everything.

I'd check with the local electric utility and ask them what they would do for depth, etc.