Hi Radu,
Well, the unusual aspect here is the thin layers sandwiched between. I am
unsure of that effect of thin layers (i.e., permeability anisotropy of
layered soils). The Strain Path Method (Teh & Houlsby, Geot. 1991) is
currently the most favored approach, yet this only addresses monotonic
dissipation of excess porewater pressures with time. If you have a filter
element on the tip or midface of the penetrometer, you always get this. If
you have the "standard" penetrometer with filter at the shoulder (alias
u_2) which is needed for the correction of measured qc to tip stress qt
(see Lunne, Robertson & Powell, 1997, Blackie Academic), then you often
have monotonic dissipations (decrease delta u with log time), but sometimes
you get dilatory response (where porewater pressures first increase, then
max, and then decrease with time). In that case, you might want to see the
paper by Susan Burns (Canadian Geotechnical Journal, Dec. 1998) as it does
both.
Sincerely,
Paul
At 05:17 PM 3/22/00 +0100, Radu Schwab wrote:
>We are doing some field investigations on a site where thin clay or coal
>layers (few
>centimeters up to few decimeters) of are embedded in a depth layer of
>fine sand.
>We had done in this thin layers some dissipation tests with CPTU and we
>are
>looking for a method to interpret the results.
>I would be very obliged if somebody could give me some information about
>this topic.
>Thanks,
>Radu
>
>
>--
>Dr. Radu SCHWAB
>Bundesanstalt fuer Wasserbau
>Postfach 21 02 53
>D-76152 Karlsruhe, Germany
>
>Tel.: +49 (0)721 9726 3810
>Fax: +49 (0)721 9726 4830
>e-mail: [log in to unmask]
>URL: http://www.baw.de
>
>
Paul W. Mayne, PhD, P.E.
Professor
Geosystems Division
School of Civil & Environmental Engineering
790 Atlantic Drive, Mason Building
Georgia Institute of Technology
Atlanta, GA 30332-0355 USA
Email: [log in to unmask]
Phone: 404-894-6226
Fax: 404-894-2281
http://geosystems.gatech.edu/
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