RE: Friction factor

From: <Conner>
Date: Thu Sep 22 2005 - 10:20:00 EDT

I don't know exactly what your application/interest is, but I believe some decades ago a gentleman named Potyondy visited the specific subject of coefficient of friction between steel and various soils in construction environments and published a perhaps significant, quite detailed paper on this subject (in that case the research may have primarily been directed toward steel pipe piles, and I believe the contact surface was somewhat "rusted" bare steel). This work was incidentally among those cited in some later work of the Ductile Iron Pipe Research Association (DIPRA) in a publication that has undergone several printings since (that is available at http://www.dipra.org/pdf/thrustRestraint.pdf).

Specifically with regard to steel water pipe, pipe to soil friction is discussed in Chapter 13 of AWWA Manual M11, "Steel Pipe -- A Guide for Design and Installation". A some different thrust restraint formula is proposed in that manual, and with the use of that formula and with other qualifications that should be read and understood in a paragraph below same, the statement is made on page 195, "Coefficients of friction are generally in the range of 0.25 to 0.40. When a high water table or submerged conditions are anticipated, the effects of buoyancy of soil must be considered." [while not specifically stated here in this section of AWWA Manual M11 I suspect the most common exterior contact material for large steel water pipes is probably tape wrap.]

The actual amount of soil/steel friction that will be developed in any specific circumstance is probably a quite complicated matter and dependent on many variables (actual contact surface material/condition, type of soil, degree of consolidation of that soil and/or contact pressures due to depth etc., degree of saturation with water or other liquids, perhaps even the amount of time before a sliding force is applied, and/or other factors.

Randy Conner

gguerrat <gguerra_geci@att.net.mx> wrote: <<<Hi

anyone knows the coefficient of friction for a buried pipe

steel_soil

thanks>>>



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