Friday, October 17, 2008

RE: Seismic Factors for Soil Nail Walls

Yes, that is huge on the fault line !  1/2 * 1.25 is gigantic, or perhaps it is better to use the 1 sec Response, so this could be 1/2 * 0.93 = 0.465, still huge. 
 
 
I found the link above which kind of says the same thing.
 
How about a temporary wall?
 
Thanks for the feedback.
Refugio

--- On Fri, 10/17/08, Mark D. Baker <shake4bake@verizon.net> wrote:
From: Mark D. Baker <shake4bake@verizon.net>
Subject: RE: Seismic Factors for Soil Nail Walls
To: seaint@seaint.org
Date: Friday, October 17, 2008, 3:40 PM

Refugio,

 

On a recent project, the geotech and I discussed his basis for the kh value he was providing. In a nutshell he said after all their research on the methods for determining kh, they concluded that they would always specify ½ of the PGA and feel comfortable with that recommendation.

 

Incorporating seismic into retaining structures certainly impacts the design of structure, ½ or more of PGA is a substantial force to account for.

 

Mark D. Baker

Baker Engineering

 

From: refugio rochin [mailto:refugio311@yahoo.com]
Sent: Friday, October 17, 2008 9:34 AM
To: seaint@seaint.org
Subject: Seismic Factors for Soil Nail Walls

 

I have a question regarding Soil Nail Walls in a high seismic region.  We are trying to identify the seismic factors for such a wall.  A geotechnical circular No. 7 

 

as well as the FHWA Soil Nail Manual, utilize the equation Am = (1.45 - A)A where A is the peak ground acceleration at 10% exceedance in 50 years.  This equation however has a maximum at 0.725, and our PGA is 1.25 to 1.1 (located on the San Andreas Fault , site specific spectra and USGS spectra, respectively).  I am not sure if this equation truly applies in this condition.

 

The target is to define the kh, which is a pseudo-static coefficient input into the Soil Nail programs.

 

Refugio


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