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RE: Modulus of subgrade reaction

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Keep in mind that the extent of the loaded area strongly effects the
subgrade modulus.  If you have a value from a 12 inch square plate test
it can be used directly for pavement deign but needs to be greatly
reduced for a large mat foundation.

Ed Marshall, PE
Atlanta, GA 

> -----Original Message-----
> From:	Windows/bob/john  On Behalf Of John Cannon Jones
> Sent:	Thursday, February 12, 1998 2:55 PM
> To:	'seaoc(--nospam--at)seaoc.org'
> Subject:	RE: Modulus of subgrade reaction
> 
> Bowles book uses modulus of subgrade reaction because it is easier to
> test for that E or v.  You can directly test for k which is better
> than test for another parameter and then calcing the one you actually
> need.
> 
> Back to the question at hand:
> 
> Contact a local geotech for this info.  In my local area values are
> typically about 150 pci.  The geotechs in this area will typically
> include this value in their reports to aid in slab design.
> 
> John Jones
> Pell City, AL
> 
> 	-----Original Message-----
> 	From:	AXB2%ENGPROJ%NTS(--nospam--at)bangate.pge.com
> [SMTP:AXB2%ENGPROJ%NTS(--nospam--at)bangate.pge.com]
> 	Sent:	Thursday, February 12, 1998 10:03 AM
> 	To:	seaoc(--nospam--at)seaoc.org
> 	Subject:	re:Modulus of subgrade reaction
> 
> 	The modulus of subgrade may be calculated from Timoshenko's
> Theory of 
> 	Elasticity (2nd Edition) formula 212, page 370, with little
> mathematical 
> 	manipulations:
> 
> 	k= E/(m(1-v^2)(A)^.5) 
> 
> 	Where:
> 	k is subgrade modulus kips/in^3 
> 	m is shape factor from accompanying table
> 	v is Poisson's ratio (v=.4 may be used)
> 	A is the area of the foundation
> 	E is modulus of elasticity of the soil (should be based on
> tests)
> 
> 	Armen
> 
> 
> 
> 	----------------------[Reply - Original
> Message]----------------------
> 
> 	Sent by:"Shafat Qazi" <seaoc-ad(--nospam--at)seaoc.org>
> 	 Question:
> 
> 	Can anyone tell me what is a standard value for the modulus of
> subgrade
> 	reaction for soil type S2?
> 
> 	I am trying to model a spring that will represent soil
> stiffness.
> 
> 	Thank you.
> 
> 	Shafat
> 
> 
> 
> 
> 	
> =====================================================================
> 
> 
> 
>