Horizontal Modulus of Subgrade Reaction

[pa24pilot]

Does anyone know if there is an accepted way of determining the horizontal modulus of subgrade reaction from a laboratory test or maybe the results from other lab tests such as direct shear? I've seen charts based on blow counts but am curious if another method, other than an it-situ test, is available.

pa24pilot

 

[Focht3]

This has been discussed before - I suggest that you do a keyword search of this site for 'modulus subgrade reaction'.

What are you designing? What is the site like? These will affect our answers.

And please remember that there is no such thing as "the" modulus of subgrade reaction - it's nothing more than a computational convenience.



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See faq158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"

 

[pa24pilot]

a horizontal modulus of subgrade reaction is needed to design a monopole cell tower (70ft in height). soils encountered at the site consist of 30+ feet of poorly graded sand. N=75+ from ~12ft down. N=9 at 5ft.

i'll do a keyword search as suggested.

thanks
pa24pilot

 

[Focht3]

The procedure you are considering is exceedingly poor for the problem that you are addressing. A far superior approach would be to use p-y curves to model the soil; p-y curves are non-linear soil support springs that are developed using soil parameters you provide. LPILE4 is the clear software industry leader in this specialized geotechnical niche; The program is well thought out and written. It is heavily supported by very knowledgeable geotechnical engineers -



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See faq158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"