Consolidation Rate
Consolidation Rate
(OP)
Hello All,
Can anyone point me to a reference on consolidation of a clay layer that is above the water table that will still be loaded above Pc. I am wondering if there is a rational/justification for using a Cv that is larger than the one from consol tests.
Thanks
Can anyone point me to a reference on consolidation of a clay layer that is above the water table that will still be loaded above Pc. I am wondering if there is a rational/justification for using a Cv that is larger than the one from consol tests.
Thanks





RE: Consolidation Rate
I wouldn’t go factoring up the Cv value and applying it to the clay above the watertable as it will give you more settlement in that layer than you probably have. If it’s non Saturated then you could just estimate settlement of that later using a modulus based method (Schmertmann etc). Then use your Cv data a one dimensional consolidation theory for the clay below the watertable.
Also, the watertable may not indicate a definitive line of what soils is saturated and non saturated. Fattdad is often highlights the above point, i believe...
RE: Consolidation Rate
RE: Consolidation Rate
You could use any conventional elastic theory method. Janbu (1998) has a method which is little different as it uses the Janbu modulus number "m". This can be calculated based on your consol data.
RE: Consolidation Rate
I think it is reasonable to expect that soil with significant air voids would settle more rapidly than soil with voids full of fluid: there is no fluid pressure to keep the void space open. However, I'm not sure on how this might be quantified. There is a book on unsaturated soil mechanics by Lu and Likos - there might be some information in this book in the sections relating to hydraulic conductivity, k (the correct term for what geotechnical engineers call 'permeability'; kv (or kh) is related to cv (or ch) by a standard equation). I've been meaning to read this book for a while, but haven't got round to it. If you do find something out, I'd be keen to hear what the conclusion to this is.
RE: Consolidation Rate
RE: Consolidation Rate
Hope you get an answer with that book.
RE: Consolidation Rate
If it is an actual problem, to avoid having to go into unsaturated soil mechanics, if the thickness of your "unsaturated" soil layer isnt too excessive (say i dunno, 3m?), could you just assume the entire layer is saturated? Then if you calculate your consolidation settlement (and immediate settlement) is less than your allowable settlement (say 25mm), then is that your problem solved?
RE: Consolidation Rate
https://core.ac.uk/download/pdf/11603128.pdf
RE: Consolidation Rate
RE: Consolidation Rate
Cv obtained from such an odometer test would reflect the dissipation of pore pressure.
You can scale Cv when using PVDs, as Ch is usually greater than Cv.
f-d
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