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RE: Seismic Earth Pressures on Cantilever Retaining Walls

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For the few soils reports I have come across with Seismic criteria for
retaining walls, all have made the seismic force a function of the height of
the wall of the top of the footing and backfill slope. The last one I did
(about 5000 lf on the side of a mountain), had functions of the following:

Uniform Seismic Load (psf):
13H (level backfill)
18H (sloping backfill 2:1)
20H (sloping backfill 1.5:1 and steeper)

I was also given different sliding coefficients and ASBP's for seismic that
did not always equate to a 1/3rd increase. I am not sure where these values
came from, but the only method I have seen to calculate seismic loads is the
one you mentioned in your original post.

good luck,
-gerard
SJ, CA

-----Original Message-----
From: J. K. [mailto:structure_r_us(--nospam--at)yahoo.com]
Sent: Monday, October 29, 2001 3:41 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Seismic Earth Pressures on Cantilever Retaining Walls


I ask this question to geotechnical engineers all the
time. Their response seems: "forget about it". Any
geotechnical engineer here?

--- Nick Arenson <narenson(--nospam--at)olymandalay.com> wrote:
> What is the state of the practice regarding seismic
> pressures on cantilever
> retaining walls?  Mononobe-Okobe (1926) developed a
> method and it has been
> extended through the years.
> 
> We've all realized that peak ground accelerations
> can be significant in near
> fault areas.  The formulation of M-O sort of falls
> apart at high
> accelerations because (it appears to me at least)
> the underlying assumptions
> can not deal with high accelerations (there is
> actually a combination of
> effects such as slope of backfill, friction angle,
> etc.,  that make the
> formulation break down).
> 
> The Seed Whitman formulation (1970) seems to still
> apply (mainly because it
> is a vast simplification and the nasty formulation
> details go away).
> 
> What are people using these days?
> 
> Nick Arenson
> 
> 
> 
> 
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