Modulus OfSoil Reaction(E')

[piping1971]

Is the a way to calculate the Modulus Of Soil Reaction(E') base modulus of subgrade reaction.Please Help!
We are checking the ring deflection of an existing buried
water pipe(20" dia.) and based on the formula we need
the Modulus Of Soil Reaction(E') but the soil test report provided the modulus of subgrade reaction.

 

[BigH]

Find a thread that gives SlideRuleEra's web site. On there he has posted several 'charts' giving relationships of various penetration/modulus parameters. SRE - can you help out and post your addy?

 

[rconner]

"...checking the ring deflection of an existing buried
water pipe" with a "formula" for some reason sounds a little strange to me, so it might be helpful to provide at least a little more information/explanation of what is going on/what you're trying to do -- also, was just curious did the "soil test report" happen to be done before or after the piping was installed, and what is the proximity of the testing location to the pipe etc.?

 

[piping1971]

there is a formula given in the book "Buried Piping Design"
but it needs the modulus of soil reaction, so i want to know if there is formula that relates "subgrade reaction"
to modulus of reaction.

 

[eric1037]

Probably the best thing to do is ask the person who provided the geotech report to give you what you need. Less liability for you.

 

[rconner]

E-prime, or the horizontal soil modulus employed in the "Iowa formula" for deflection of flexible pipes, has been reported by various researchers to involve interaction with, or be in some cases a rather complex function of, the specific soil type and density, pipe/soil depth, and also the ring stiffness of the specific pipe/material involved. Ring stiffness of differing pipe materials in an of itself can be a rather complex subject, as some materials can deflect more over time than others (long-term moduli for example of plastics can be markedly less than that determined from standardized rapid loading rate laboratory tests, due to creep etc.) Also, if the native soil for example in which a pipelaying trench is dug has markedly different support or void characteristics than the pipe backfill zone, this along with the trench width may also have bearing on effective E-prime as well. While I guess it is possible some "geotech" folks understand all of these interactions and might give you a simple answer to your general question, perhaps any simplifications of such complex matters without detailed information need to be carefully considered/conservative.