Skin Friction value for crushed stone
Skin Friction value for crushed stone
(OP)
Problem: A smooth round concrete pole embedded into an augered hole and backfilled with a compacted stone (using long-stemmed vibrators); more specifically, a #57 Florida DOT crushed limerock (essentially, the coarse aggregrate for a concrete mix).
Question: what is a conservative value to use for skin friction (psf) of the pole against the compacted rock to resist the vertical load?
Question: what is a conservative value to use for skin friction (psf) of the pole against the compacted rock to resist the vertical load?





RE: Skin Friction value for crushed stone
However, that compacted filled hole then is against native earth which may have a much lower shear value value (but larger perimeter).
Also you need to think about the characteristics of the stuff you are pulling against, which is the nearby earth. In that case the chunk of anchoring land is an inverted cone of some unit density. The angle of the cone sides respect to that pole depends on the shear strength of that earth. If it is under water that makes a difference also.
I assume you knew that, sorry. More things to look at for these cases than what you asked for.
RE: Skin Friction value for crushed stone
Thanks for the info. I'm amazed that it could be so high. So, when it comes to crushed rock, I guess there isn't much of a relationship that you could draw between the skin friction and its friction angle as there would be with sand?
BTW, having been around since 1933, I might be able to challenge you for your title, but I'd still be willing to let you keep your adopted name.
http://www.spiraleng.com
RE: Skin Friction value for crushed stone
RE: Skin Friction value for crushed stone
Thanks for the response.
A concrete backfill is always better as far as performance and interaction with the soil is concerned, but when dozens of poles are to be placed in a line, the contractors have an aversion to holding each one with a crane long enough for the concrete to set.
http://www.spiraleng.com
RE: Skin Friction value for crushed stone
How about 1928?
RE: Skin Friction value for crushed stone
I graciously concede. I've always have respect for my elders.
http://www.spiraleng.com
RE: Skin Friction value for crushed stone
RE: Skin Friction value for crushed stone
My mission is to come up with a reasonable value to use for skin friction of the compacted rock against a smooth concrete pole. The vertical resistance against the axial load is our concern here.
http://www.spiraleng.com
RE: Skin Friction value for crushed stone