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RE: Retaining Wall Design Methodology

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Title: RE: Retaining Wall Design Methodology

Charles:

I certainly don't want to leave you puzzled!  Obviously, there is substantial downward soil pressure on the top of the heal.  That pressure is present in all three methods, and is not the issue.  Rather, the issue is how to treat upward soil bearing pressure on the bottom of the heal when designing the heal for moment and shear.  Method #1 ignores this pressure altogether, leaving the heal acting as a heavily loaded cantilever.  As I pointed out previously, for tall walls (say, above ten feet), this greatly increases the heal thickness and reinforcement.

At Halff Associates, we have just about concluded that Method #3 should be our future standard.  Based on test results, it appears to best represent what is actually happening.  It also appears to consistently produce reasonable results.

Regards,

Stan Caldwell in Dallas

***********************************************************************
"You can say any foolish thing to a dog, and the dog
will give you a look that says, 'My God, you're right! 
I never would've thought of that!" --- Dave Barry
***********************************************************************

-----Original Message-----
From: Charles Greenlaw [mailto:cgreenlaw(--nospam--at)speedlink.com]
Sent: Wednesday, July 12, 2000 7:44 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Retaining Wall Design Methodology


Stan, you seem to be apportioning only upward soil pressures on the wall
footing. If that is so, then why even have a heel feature?  Upward pressure
on the heel does not help with stability of the wall.

The heel is useful for downward pressure the backfill imposes on it, which
helps stability against overturning. The heel experiences negative moment
for reinforcing purposes.

I assume you know all this perfectly well, which makes your question
puzzling for why the matter is of interest.

Charles O. Greenlaw SE    Sacramento CA