qc value to SPT N60 value

[PeacefulWarrior]

Can you please help me out with this problem. This is my first term in geotech eng.

A cone penetration test on a sandy soil with mean particle size of .5 mm produced a qc of 80kg/cm^2. Estimate the equivalent SPT N60-value.

I understand how to calculate a SPT N60 value, but I don't know the ratio between the N60 and the qc value of a CPT. I have looked all through my textbook and there are no example problems, nor do they explain the ratio.

Please help.

Thank you

 

[BigH]

Look up Schmertman's relationships

 

[GoodnightKiwi]

Have a read over the attached pages from a document by Prof Robertson. This might help with your correlation.

Full document can be obtained free from:

http://www.greggdrilling.com/Resources/CPTforGeotechnicalGuide/CPTguiderequestpage.htm