I do not know the cited reference but 

Poulos, H.G., and Davis, E.H. "Pile foundation analysis and design", 1980 

Has a Figure 4.12 which relates Liquidity Index to Toe damping, which is
based on Coyle and Gibson, 1970, "Empirical Damping Constants for Sands and
Clays", JSMFD, ASCE, vol. 96, SM3, pp. 949-965.  The P & D book also
suggests a ratio between shaft and toe damping.

Either of these documents should be easy to obtain.  You can correlate the
LI to undrained shear strength for NC clays, but from the sounds of it,
would have to make another correction for OCR.  The multi-stage empiricism
will probably lead to an excessive range of values, such that you might be
better off to just stick to presumptive values to begin with.

I have not, personally, ever used the foregoing so cannot comment on its
validity, but it might be of help to you.  PDA results analyzed with
something like CAPWAP should generate damping values as well, if you can
drive a test pile.  In my experience, however, the shaft values are a
weighted average, so if you are in a multi-layer soil you won't be much
better off.

Regards, Mike
   
Michael R. Bleakney, P. Eng.
Geotechnical Engineer 
New Brunswick Department of Transportation
Structures and Materials Branch
PO Box 6000
Fredericton, New Brunswick
CANADA
E3B 5H1

Tel: (506) 453-2674
Fax: (506) 457-6714
Email: [log in to unmask] <mailto:[log in to unmask]> 

	-----Original Message-----
	From:	Eric Parker [SMTP:[log in to unmask]]
	Sent:	Wednesday, January 12, 2000 5:05 AM
	To:	[log in to unmask]
	Subject:	Roussel soil damping parameters

	Hello,
	 
	We are working on a pile driveability job in hard clays.  I am
looking for the "Roussel 1979" soil damping parameters which correlated wave
equation damping to undrained shear strength.  The original publication was:
	 
	Roussel H.J., 1979, Pile driving analysis of large diameter high
capacity offshore pipe piles, Ph.K Thesis, Department of Civil Engineering,
Tulane University, New Orleans, Louisiana.
	 
	Unfortunately, this is difficult to obtain.  Does anyone know of a
source which gives Roussel's conclusions regarding damping?
	 
	Thanks
	 
	Eric Parker
	D'Appolonia S.p.A.


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