soil friction force

[B.L.Smith]

Dear Frineds

I'm not a civil eng. and I have a basic question:

Suppose two same material and density pipes:
1- A 50 meters carbon steel pipe on 5 steel pipe support.
2- A 50 meters carbon steel pipe on the dry ground(not buried).
which of them does need greater force for moving?

 

[rconner]

This is one of those "it depends" type questions (due to not much info supplied in the inquiry, which may be why there is little response). You don't say what the steel pipe or support is painted or coated with(maybe some unusual if it were not painted?), that I guess could conceivably make a difference, and you don't identify type of soil or moisture conditions of anything etc. Nevertheless, I am going to say that I think in most cases it would probably be at least a little harder to slide steel pipe along the ground than would to move clean bare steel on a clean steel support. That may not win you a bet for a beverage of choice with a colleague! (Put a pad of rubber between the support and pipe, and I wouldn't be a bit surprised if it were the other way around.)

 

[BigInch]

Same pipe weight, if it is the same friction factor = same total friction force, distributed differently. Friction is either distributed uniformly (lbs/ft) where the pipe is in contact with soil, or collected to concentrated loads at supports.

Independent events are seldomly independent.