OCR less than 1
OCR less than 1
(OP)
I have seen quite a bit of samples with overconsolidation ratio (OCR) less than 1 (from oedometer tests). Some have told me that it is a testing artefact due to disturbance of the soil, they say technically OCR cannot be less than 1. Some others say that this is due to the fact that the samples are still undergoing consolidation, so the P'c hasn't reached the final P'c at 100% consolidation. What do you think?





RE: OCR less than 1
RE: OCR less than 1
RE: OCR less than 1
RE: OCR less than 1
Two of the sites where I am working on with OCR < 1, one was in an area where there was regional groundwater dewatering, one had large areal fills placed recently on top of soft clays. So in my opinion these samples were under onsolidated, but there were quite many seniors who disagree, saying that it is impossible that OCR can be less than 1. I think many textbooks don't deal with OCR < 1 too.
RE: OCR less than 1
RE: OCR less than 1
...absolutely
RE: OCR less than 1
f-d
¡papá gordo ain’t no madre flaca!
RE: OCR less than 1
Just to take this a bit further:
Suppose a soil element had an original effective stress of 100kPa, and a fill of 60kPa was added to it. The current P'c is 130kPa. Can I reasonably assume that the degree of consolidation = 50% based on (130-100)/(160-100)?
RE: OCR less than 1
RE: OCR less than 1
I agree that the degree of consolidation, U(%) is defined based on settlement. The reason I'm asking this is that I may have to backcalculate remaining consolidation settlements from underconsolidated soft clays, and I believe the excess pore pressures can give me quite a good idea of how much remaining settlement there is.