Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Foundation Soil Characteristics by Surface Wave Sounding

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Nels-
What you appear to be looking for is a geophysical firm. Contact your favorite geotech and they can probably recommend someone if they don't do it themselves. I have been involved in several projects here in Northern California where we have used such services to supplement the information obtained by borings to better delineate subsuface features such as faults and geologic contacts and generate velocity profiles.  The soundings are produced either by small explosive charges or stiking an anvil with a mallet and reading the resulting vibrations with goephones at various distances from the vibration source. 
 
One generally doesn't use geophysical techniques by themselves but rather in conjunction with other geotechnical information. In one case we were looking to supplement subsurface information for a water tunnel, in another, information on a fault's orientation near a geothermal drilling site.  The information can provide a profile of velocities along the geophysical line as well as the orientation of the planar features (such as faults and contacts).  Basic soil mechanics can then be used to estimate other properties. 
 
In tunnels, 3D representations of the ground ahead are sometimes developed by what is called computerized tomography which utilizes geophysical methods similar to a medical CAT scan.  Some geophysical firms also use similar techniques for surface-based explorations.
 
Bill Cain, S.E.
Berkeley CA
 
 
-----Original Message-----
From: Daryl Richardson <h.d.richardson(--nospam--at)shaw.ca>
To: seaint(--nospam--at)seaint.org
Sent: Fri, 02 Dec 2005 10:29:20 -0700
Subject: Re: Foundation Soil Characteristics by Surface Wave Sounding

Nels,
 
        This sounds a little bit like a seismic investigation similar to what might be used in petroleum prospecting.  You might try looking in that direction.
 
Regards,
 
H. Daryl Richardson
----- Original Message -----
Sent: Thursday, December 01, 2005 4:20 PM
Subject: Foundation Soil Characteristics by Surface Wave Sounding

Can you recommend references to the use of a surface wave sounding to provide a shear wave velocity model of the upper 100 feet of a site?  The soil parameters to be evaluated in this way are ultimate and allowable bearing pressures; elasto-plastic spring constants for shallow spread footings; and elastic and shear moduli.
 
Are the results of this kind of evaluation likely to be about the same as the results of a more conventional soils investigation?
 
Nels Roselund, SE
South San Gabriel, CA

From: Chance, Acie [mailto:AChance(--nospam--at)lacsd.org]
Sent: Thursday, December 01, 2005 1:26 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: wrong crack monitor
 
Doug
 
    Do you monitor all lists or are we the only ones you bless with your years of experience.  This thread is about Structural Engineers monitoring cracks over time (read weeks to years).  I would not count on wet paper to stay in position for more then a few hours. 
 
Acie Chance
-----Original Message-----
From: AmerRescue(--nospam--at)aol.com [mailto:AmerRescue(--nospam--at)aol.com]
Sent: Thursday, December 01, 2005 12:36 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: wrong crack monitor
In a message dated 12/1/2005 12:59:39 P.M. Atlantic Standard Time, jccpc(--nospam--at)msn.com writes:
Wet paper stretches. It also does not tear suddenly. Glass microscope slides makes a better telltale as it is brittle and has little elongation, however, uneven surfaces make adhesion difficult. Both will only show enlarging of a crack, not closure, and the paper will be restricted to planar movement. Across uneven surfaces it will be wavy/creased which will allow additional movement before tearing. Additionally, it will not stick effectively unless the surfaces are very clean. The same problem (regarding surface cleanliness) occurs with epoxy. At a collapse site theodolites are preferred as they also allow remote monitoring. While in the collapsed building falling dust and noise make an excellent telltale.
 
You are wrong. That is the way rescuers whose lives are at stake, have ACTUALLY been doing it , from many countries, for many years. It sticks easy and wet paper tears at the slightest movement of any kind.
 
doug copp