spd60
Civil/Environmental
- Nov 10, 2006
- 11
- 0
- 0
Does anyone know or recommend what modulus of pipe embedment should be used in the spangler equation for buired pipe deflection when the embedment and backfill material will be unshrinkable fill.
Eng-Tips is the largest engineering community on the Internet
Intelligent Work Forums for Engineering Professionals
-
Congratulations waross on being selected by the Tek-Tips community for having the most helpful posts in the forums last week. Way to Go!
Modulus of Soil Reaction
- Thread starter spd60
- Start date
- Status
you can probably use somewhere between 50 to 100 MPa (7 to 15 psi)
Check that here, where you can find just about any typical values you will ever need and many you never will.
BigInch![[worm]](/data/assets/smilies/worm.gif "[worm] [worm]")
-born in the trenches.
Check that here, where you can find just about any typical values you will ever need and many you never will.
BigInch
-born in the trenches.I just happened to run across this one
Calculate E' by American Concrete Pipe Asso.
BigInch-born in the trenches.
Calculate E' by American Concrete Pipe Asso.
BigInch
-born in the trenches.- Thread starter
- #4
Oops! Don't use the values I gave above. Use the Caltrans values and calculate E' using my second reference.
BigInch-born in the trenches.
BigInch
-born in the trenches.I also figured out its nice to post the url to the TOC of a pdf document, so here it is,
BigInch-born in the trenches.
BigInch
-born in the trenches.If you are talking about the E-prime, or the horizontal soil modulus employed in the "Iowa formula" for deflection etc. of flexible pipes, this parameter in general has been reported by various researchers to involve interaction with, or be in some cases a rather complex function of, specific backfill type and density, pipe/soil depth, and also the ring stiffness of the specific pipe/material involved. Ring stiffness of differing flexible pipe materials in an of itself can be a rather complex subject, as some materials can deflect more over time than others and profile wall pipes may have a wider range of localized stress/strain levels at a given deflection than solid wall pipes (and 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., or maybe even the room temperature moduli often reported for flexible pipes will be reduced by the significant heat generated during long-term curing of flowable fills?) Also, if the native soil for example in which a pipe laying 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.
Flowable fills in and of themselves may also be subject to significant local (mix etc.) variations. All of this should probably be considered depending on the specific application conditions.
All this being said, while specific sidefill etc. pipe support research or references re flowable fill may be some hard to come by I believe most promoters of even the lower strength "excavatable" flowable fills claim that these materials have anywhere from "equivalent" to many times the "allowable bearing strength" of previously used compacted soils in other engineering applications. If this is the case, one would of course at least intuitively feel that properly mixed and installed flowable fill installations would in general result in very good pipe support, at least to metal pipes.
While E-prime is not a pure backfill material property as I've explained above, I have noticed that the latest version (now in 4th ed. 2004) of AWWA Manual M11, Steel Pipe - A Guide for Design and Installation does discuss use of "constrained soil modulus", a "constitutive material property" for soils, that (values) might also be available or determinable for at least some flowable fills and native soils etc.
Flowable fills in and of themselves may also be subject to significant local (mix etc.) variations. All of this should probably be considered depending on the specific application conditions.
All this being said, while specific sidefill etc. pipe support research or references re flowable fill may be some hard to come by I believe most promoters of even the lower strength "excavatable" flowable fills claim that these materials have anywhere from "equivalent" to many times the "allowable bearing strength" of previously used compacted soils in other engineering applications. If this is the case, one would of course at least intuitively feel that properly mixed and installed flowable fill installations would in general result in very good pipe support, at least to metal pipes.
While E-prime is not a pure backfill material property as I've explained above, I have noticed that the latest version (now in 4th ed. 2004) of AWWA Manual M11, Steel Pipe - A Guide for Design and Installation does discuss use of "constrained soil modulus", a "constitutive material property" for soils, that (values) might also be available or determinable for at least some flowable fills and native soils etc.
- Thread starter
- #8
spd60
Civil/Environmental
- Nov 10, 2006
- 11
- 0
- 0
Whew, took a while to get back to you all. Thanks again for the help.
After some phone calls, internet searches and speaking with a helpful geotechnical engineer I found references to research papers and industry publications that established E' values for unshrinkable fill.
In summary, it's a valid assumption to assume that the ufill will have equivalent E' values to about 1000-1500 psi after a short time of setting up.
After some phone calls, internet searches and speaking with a helpful geotechnical engineer I found references to research papers and industry publications that established E' values for unshrinkable fill.
In summary, it's a valid assumption to assume that the ufill will have equivalent E' values to about 1000-1500 psi after a short time of setting up.
01011959 Wrong website. Try
BigInch-born in the trenches.
BigInch
-born in the trenches.- Status
Similar threads
- Locked
- Question
- Locked
- Question
- Locked
- Question
- Locked
- Question
