PERMANENT DEFORMATION CHARACTERIZATION OF SUBGRADE SOILS FROM RLT TEST

The practice of the American Association of State Highway and Transportation Officials (AASHTO) for designing flexible pavements requires resilient modulus of the subgrade soils. The resilient characteristics are assumed to account for the permanent deformations of soils. However, this approach can provide misleading characterizations. Soils such as silty sands, silty clays, and sandy clays possess good resilient characteristics. Nevertheless, they still undergo large plastic deformations under traffic loads. Hence, both elastic and plastic strain responses are necessary for a complete characterization. This paper presents an evaluation on the repeated load triaxial (RLT) test method for providing the permanent strain response of the soils. RLT tests were conducted on three soil types: well-graded sand, silty clay, and heavy clay. Tests provided the plastic strain data at various confining deviatoric stresses and loading cycles. Data were analyzed with a plastic strain formulation that accounted for stresses and loading cycles. The formulation has reasonably represented the plastic strain response in these soils. Formulation predictions agree with the measured permanent strain results of a field site subjected to accelerated loading. Future research needs are also discussed.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/08991561
• Supplemental Notes:
  • This work was supported by the LTRC in cooperation with the Louisiana Department of Transportation and Development state Project No. 94-2GT.
• Corporate Authors:

  American Society of Civil Engineers

  1801 Alexander Bell Drive
  Reston, VA  United States  20191-4400
• Authors:
  • Puppala, A J
  • Mohammad, L N
  • Allen, A
• Publication Date: 1999-11

Language

• English

Media Info

• Features: Appendices; Figures; Photos; References; Tables;
• Pagination: p. 274-282
• Serial:
  • Journal of Materials in Civil Engineering
  • Volume: 11
  • Issue Number: 4
  • Publisher: American Society of Civil Engineers
  • ISSN: 0899-1561
  • EISSN: 1943-5533
  • Serial URL: http://ascelibrary.org/journal/jmcee7

Subject/Index Terms

• TRT Terms: Accelerated tests; Confining pressure; Deformation; Deviatoric stress; Elastic deformation; Flexible pavements; Modulus of resilience; Pavement design; Plastic deformation; Regression analysis; Repeated loads; Sand; Sandy clays; Silty clays; Silty sands; Soils; Strain (Mechanics); Subgrade (Pavements); Subgrade materials; Test procedures; Traffic loads; Triaxial shear tests
• Identifier Terms: American Association of State Highway and Transportation Officials
• Subject Areas: Data and Information Technology; Design; Freight Transportation; Geotechnology; Highways; Pavements; I22: Design of Pavements, Railways and Guideways; I42: Soil Mechanics;

Filing Info

• Accession Number: 00778240
• Record Type: Publication
• Contract Numbers: 94-2GT, LEQSF (93-96)-RD-3-12
• Files: TRIS
• Created Date: Nov 29 1999 12:00AM