Preconsolidation Pressure

[Geotechnical76]

Is there any correlation or formula that describes how to ESTIMATE the preconsolidation pressure when the consolidation test data are not available?
Thanks

 

[fattdad]

Seeing as how ESTIMATE is in capital letters, you will likely find several methods (i.e., guesses) - ha. How about:

Take the undrained shear strength and figure out what the confining stress would have to be based on Su/P of 0.2 and then comparing that to the effective overburden pressure?

Or, figure that clay with a natural moisture content at the liquid limit is normally consolidated and clay at the plastic limit is pretty overconsolidated. So if it's somewhere inbetween it's pre-consolidated?

If you are just slightly loading the soil, I'm often comforted in knowing that the liquid limit is well above the natural moisture content and the unconfined compressive strength is well in excess of the Su/P ration of 0.2. I really don't try to calculate the OCR as an interim step - then again, I know my market and the soils in the area pretty well. If I was working in an area I didn't know that well and the loading conditions were likely to affect a clay layer, I'd just do a consolidation test.

f-d

¡papá gordo ain’t no madre flaca!