PREDICTION OF SUBGRADE MODULI FOR SOIL THAT EXHIBITS NONLINEAR BEHAVIOR

The main objective of this report is to develop a simple and accurate procedure to predict an equivalent one-layer subgrade modulus for a soil that exhibits nonlinear behavior in a flexible highway pavement system. The analysis is predicated on developing such a modulus that would yield identical values of either vertical strain on deflection at the top of the subgrade compared with results obtained from a stress-dependent iteration technique that accounts for the stress-dependent (nonlinear) behavior of the subgrade. Use of a modified elastic layered computer program was made to determine equivalent subgrade modulus values for nearly 3900 separate layered pavement problems. By using the results obtained, multiple regression techniques were used to determine predictive equations for the equivalent subgrade modulus values as a function of the nonlinear subgrade and layered pavement properties. Use of partial model regressions techniques allowed predictive equations to be obtained that had correlation coefficients in excess of 0.95 and residual errors less than 10 percent. Both analytical and nomographic solutions are presented to demonstrate the simplicity of the approach. It was found that values of deflection-based equivalent modulus are larger than or equal to values of strain-derived modulus for a given set of load, pavement, and nonlinear subgrade properties. Although the vertical subgrade-strain-derived subgrade moduli are generally independent of the incorporation of overburden stresses, equivalent subgrade moduli based on deflection criteria, without overburden considered, were almost always larger than equivalent deflection based moduli developed with overburden incorporated into the analysis. (Author)

• Record URL:
  • http://onlinepubs.trb.org/Onlinepubs/trr/1981/810/810-002.pdf
• Record URL:
  • https://scholar.google.com/scholar_lookup?title=PREDICTION+OF+SUBGRADE+MODULI+FOR+SOIL+THAT+EXHIBITS+NONLINEAR+BEHAVIOR&author=J.+Moossazadeh&author=M.+Witczak&publication_year=1981
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/0309032512
• Supplemental Notes:
  • Publication of this paper sponsored by Committee on Flexible Pavement Design. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
• Authors:
  • Moossazadeh, Jan
  • Witczak, Matthew W
• Publication Date: 1981

Media Info

• Media Type: Print
• Features: Figures; References; Tables;
• Pagination: pp 9-17
• Monograph Title: Layered pavement systems
• Serial:
  • Transportation Research Record
  • Issue Number: 810
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Coefficient of subgrade reaction; Computer programs; Deflection; Equations; Flexible pavements; Forecasting; Multiple regression analysis; Nonlinear systems; Overburdens; Pavements; Stresses
• Uncontrolled Terms: Nonlinearity; Vertical stress
• Old TRIS Terms: Highway pavement; Multiple regression
• Subject Areas: Geotechnology; Highways; Pavements; I42: Soil Mechanics;

Filing Info

• Accession Number: 00345301
• Record Type: Publication
• ISBN: 0309032512
• Files: TRIS, TRB
• Created Date: Jan 29 1982 12:00AM