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Topic: Geotechnical design and analysis
Subject: modulus of subgrade reaction
Author: yinka adewuyi 2001-05-24  

Is there any literature that addresses an estimation
of modulus of subgrade reaction? I am new to the concept and would appreciate your assistance.



  Author: Ivana Spasojevic 2001-06-08  
  Yes, there's a paper "Evaluation of Coefficients of Subgrade Reaction" by Karl Terzaghi. I'm also looking for it but it seems that it's not available on the Internet. Does anyone has these presumptive values for different soil types? I'd appreciate if someone could scan it and send it using my private e-mail address ivanaspa@ptt.yu

Thanks a lot!

Best regards,
Ivana Spasojevic

  Author: Tom Sklucki 2001-06-15  
  Modulus of subgrade reaction empirical determination based on plate bearing
tests is discussed in the 1955 Terzaghi paper.
Terzaghi K, Evaluation of Coefficient of Subgrade Reaction,
Geotechnique Vol.5, No.4, 1955

The topic is covered quite well in Joseph E. Bowles' book
'Foundation Analysis and Design' 5th Edition 1996 section 9.6 pp 501-506.

Bowles gives Vesic formula relating modulus of subgrade reaction to the
elastic modulus and Poisson's ratio.

Bowles suggests approximate modulus based on:
40 times ULTIMATE bearing capacity in kPa/m (kilopascal per square metre
per metre) or 12 times ultimate bearing capacity in k/ft3 (thousand pounds
per square foot per foot). Where ultimate b.c. is allowable b.c.
'furnished by the geotechnical consultant' (sic) times the safety factor
(possibly also furnished by the geotechnical consultant?).

Bowles gives formulae for estimating the modulus of subgrade reaction using
the Terzaghi or Hansen bearing capacity factors.

Bowles gives some typical ranges of the modulus in kPa/m (that's kilopascal
per metre) for soils but only AS A VERY ROUGH GUIDE
loose sand 4800-16000
medium dense sand 9600-80000
dense sand 64000-128000
clayey medium dense sand 32000-80000
silty medium dense sand 24000-48000
clayey soil (allowable bearing capacity 200 kPa or less) 12000-24000
clayey soil (a.b.c 200 kPa to 800 kPa) 24000 - 48000
clayey soil (a.b.c greater than 800 kPa) more than 48000
(Bowles specifically warns you NOT to pick a middle value in these ranges
and provides the table as a check on your calculated value using one of
the approximations he gives)

see also
US Navy design manual published by NAVFAC (Naval Facilities Engineering Command)
NAVFAC DM 7.01, Soil Mechanics, 1 September 1986
available free as Adobe Acrobat file DM7_01.PDF which may be downloaded from

....Chapter 5 Figure 6 provides a correlation between relative density and modulus of subgrade reaction for cohesionless soils

see also
NAVFAC DM 5.4, Civil Engineering Pavements, October 1979 1986
available free as Adobe Acrobat file DM5_4.PDF which may be downloaded from
.....Figure 3 provides an approximate relationship between modulus of subgrade reaction and California Bearing Ratio
....Table 2 is supposed to provide approximate values of modulus of subgrade reaction for various soils however this table is NOT in the downloaded PDF file because it is a fold-out page.(maybe it's too big for their scanner).
In this document the advice is not to use estimated
values of subgradereaction modulus more than 300
(pounds per square inch per inch) unless substantiated
by in-situ plate bearing tests and not to use values
more than 500 (pounds per square inch per inch)
regardless of test results.

>>>>>>>>>>>end of posting

  Author: yinka adewuyi 2001-06-16  
  Hi Tom Sklucki

Thanks a lot for the info.
Do you have the documents? I tried downloading them but was not successful. If you do please send them to me by email.



  Author: Rao 2004-06-11  
  "Evaluation of Coefficients of Subgrade Reaction" by Karl Terzaghi published by Institution of Civil Engineers, London.  

  Author: kayode familoni 2004-09-13  


  Author: Maryam Akbarzad 2005-01-19  
  Dear sir
My name is Maryam Akbarzad and I am doing an MS in Geotechnical Engineering at the University of Tabriz. My subject of thesis is Investigaion about equations and the methods of estimation of the coefficient of subgrade reaction and analysis of the sensitivity of it in design of foundations and retaining walls. that would be very kind of you to provide me with any more lectures, books and etc.
best regards

University of Tabriz - IRAN
Faculty of Civil Engineering - Department of Geotechnical Engineering
Maryam Akbarzad

  Author: Carlos Vasconcellos B 2005-01-28  
  Dear Sir:

Could you send me the information about the values of the modulus of subgrade reaction.

Best Reagrds

Carlos Vasconcellos B
Lima - Perú

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Ivana Spasojevic, 2001-06-08
Tom Sklucki, 2001-06-15
yinka adewuyi, 2001-06-16
Rao, 2004-06-11
kayode familoni, 2004-09-13
Maryam Akbarzad, 2005-01-19
Carlos Vasconcellos B, 2005-01-28

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