Dear Awad,
"Cohesion" is an especially confusing term to use, as it implies two
distinct and different parameters. The correct use is for the "effective
cohesion intercept" or c' that is the Apparent Intersection of the
Mohr-Coulomb strength envelope with the Ordinate axis of shear stress vs.
effective normal stress. Of course, Mohr-Coulomb is a forced linear fit to
an actually curved & complex yield surface, thus c' itself is anything but
fundamental. For this, please see:
http://www2.eng.cam.ac.uk/~ans/
and also the nice summary of c' backcalculated from slope failures and
measured c' from lab tests in Mesri & Abdel-Ghaffar (Aug. 1993, ASCE
Journal of Geot. Engrg.). Also a little in Mayne & Stewart (Nov. 1988,
ASCE JGE): c'/pc' = 0.04 (where pc' is preconsolidation stress).
On the other parameter, c = "cohesion", but this has long been replaced
with the term "Undrained Shear Strength" and represented by either c_u or
s_u. There are so many references on this topic of normalized undrained
shear strength to effective overburden ratio, formerly represented by the
old antiquated nomenclature = c/p' ratio, but now (c_u/S_vo') or
(s_u/S_vo') [sorry, can't do Greek symbols here]. Anyhow, check out the
following for this:
Ladd, C.C. (1991, April), ASCE JGE (Terzaghi Lecture).
Jamiolkowski, M. et al. (1985), Vol. 1, Intl. Conf. on Soil Mechanics &
Foundation Engineering, San Francisco.
There is a listing of references on clays with cu/Svo' ratios from
different tests in Mayne (Jan. 1988, JGE) and note that equation (1) is
missing the exponent term: Capital Lambda.
Respectfully,
Paul W. Mayne
At 10:47 AM 9/21/99 +0300, Al-Karni Awad A. wrote:
>Dear member,
>
>Please send me any information that you have on the relationship between
>the cohesion parameter (C) with the overburden pressure.
>
>Thanks,
>
>Awad Al-Karni
>
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>
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