CONSTITUTIVE EQUATION FOR PERMANENT STRAIN OF SAND SUBJECTED TO CYCLIC LOADING

Numerous rational methods for flexible pavement design and rehabilitation have been proposed to overcome some of the deficiencies of current empirical methods. Most of these rational methods predict permanent deformation in subgrade materials so that a pavement structure may be selected that will limit permanent deformation under the application of traffic loads. Thus, procedures for characterizing permanent deformation of subgrade materials are required in each of these methods. This paper presents a constitutive equation for predicting accumulated permanent strain of sand subgrade material after any number of repetitions of load. The parameters needed as input to the equation are obtained from a static triaxial test. To develop the equation, duplicate samples were tested by using both static triaxial apparatus and a closed-loop electrohydraulically actuated triaxial system. The dynamic test results were normalized with respect to parameters obtained from the corresponding static triaxial test. The difference in the normalized cyclic principal stress showed a unique relationship to the normalized accumulated permanent strain. This relationship was found to be independent of moisture content, density, and confining pressure. Based on these findings, a constitutive equation for permanent strain was developed. (Author)

• Record URL:
  • http://onlinepubs.trb.org/Onlinepubs/trr/1981/810/810-007.pdf
• Record URL:
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• Supplemental Notes:
  • Publication of this paper sponsored by Committee on Strength and Deformation Characteristics of Pavement Sections. 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:
  • Lentz, Rodney W
  • Baladi, Gilbert Y
• Publication Date: 1981

Media Info

• Media Type: Print
• Features: Figures; References;
• Pagination: pp 50-54
• Monograph Title: Layered pavement systems
• Serial:
  • Transportation Research Record
  • Issue Number: 810
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Deformation; Dynamic tests; Equations; Flexible pavements; Pavement design; Repeated loads; Sand; Static tests; Strain (Mechanics); Subgrade (Pavements); Traffic loads; Triaxial shear tests
• Old TRIS Terms: Strains
• Subject Areas: Freight Transportation; Geotechnology; Highways; Pavements; I42: Soil Mechanics;

Filing Info

• Accession Number: 00345306
• Record Type: Publication
• ISBN: 0309032512
• Files: TRIS, TRB
• Created Date: Jan 29 1982 12:00AM