Relationship between N value and phi in deep foundation

[Reston]

I am looking for if there exists any relationship between no of blows N and phi.As we have between N and Cohesion.

Thanks

Reston

 

[Reston]

I forgot to mention that I need N-Phi relationship in silty clayey or clayey soils. Is there anyone who could help me?

Reston

 

[jdonville]

Reston,

Suggest you use relations correlating phi for cohesive soils and PI presented as Figure 3-4 in USACE EM 1110-2-2504.

Jeff

 

[PSlem]

http://www.vickars.com/screwpile_manual/PDF_Files/Step4-BearingCapacity.pdf

 

[jdonville]

Reston,

Suggest you convert your SPT N values to N60 values for use with Bowles' correlations per PSlem's reference.

Jeff

 

[jdonville]

Reston,

Oops - just noticed that PSlem's reference shows correlation for non-cohesive soils, so it won't be direclty applicable to silty clay or clay soils.

Jeff

 

[Donrolla]

I would hesitate to use correlations between N value and phi in clayey soils with silt or sand....you need to do some lab testing.

 

[Reston]

Thank you very much all for great help

Reston