SOME BASIC PROBLEMS IN FLEXIBLE-PAVEMENT DESIGN

WITH RESPECT TO THE STRESSES APPLIED BY WHEEL LOADS TO AIRPORT AND HIGHWAY SURFACES, ONE OF THE BASIC PROBLEMS OF FLEXIBLE PAVEMENT DESIGN IS THAT THE SHEARING STRENGTHS OF THE LAYERS OF FLEXIBLE PAVEMENT CLOSE TO THE LOADED AREA, I.E., OF THE BASE COURSE AND BITUMINOUS SURFACE, MUST BE HIGH ENOUGH THAT FAILURE ALONG SHEAR SURFACES ENTIRELY WITHIN THE BASE AND SURFACE WILL NOT OCCUR. VALUES FOR EACH LAYER OF THE FLEXIBLE PAVEMENT ARE BEING DETERMINED BY MEANS OF THE TRIAXIAL TEST, AND UPON THE ASSUMPTION THAT THE SURFACES OF SHEARING FAILURE ARE LOGARITHMIC SPIRALS. BY TRIAL AND ERROR, THE POSITION OF THE CRITICAL LOGARITHMIC SPIRAL IS LOCATED ALONG WHICH THE SHEARING RESISTANCE OF THE MATERIALS WILL SUPPORT THE SMALLEST ULTIMATE APPLIED LOAD. THE WHEEL LOAD AND TIRE PRESSURE FOR WHICH THE FLEXIBLE PAVEMENT IS DESIGNED MUST NOT EXCEED THIS ULTIMATE STRENGTH AFTER IT HAS BEEN REDUCED BY A SUITABLE SAFETY FACTOR. IN ESSENCE, THIS METHOD INVOLVES THE DETERMINATION OF VALUES FOR AN EQUAVALENT HOMOGENEOUS MATERIAL HAVING THE SAME ULTIMATE STRENGTH AS THE LAYERED SYSTEM OF THE FLEXIBLE PAVEMENT. THE ULTIMATE STRENGTH OF THIS EQUIVALENT HOMOGENEOUS MATERIAL IS CALCULATED ON THE BASIS OF A LOGARITHMIC SPIRAL FAILURE SURFACE. /AUTHOR/

• Record URL:
  https://onlinepubs.trb.org/Onlinepubs/hrbproceedings/32/32-006.pdf
• Supplemental Notes:
  • Vol 32, pp 90-118, 12 FIG, 5 TAB, 30 REF, APP. 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:
  • Mcleod, N W
• Publication Date: 1953

Media Info

• Media Type: Digital/other
• Monograph Title: Proceedings of the Thirty-Second Annual Meeting of the Highway Research Board, Washington, D.C., January 13-16, 1953
• Serial:
  • Highway Research Board Proceedings
  • Volume: 32
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Failure; Flexible pavements; Pavement design; Shear strength; Stresses; Triaxial shear tests; Ultimate strength; Wheel loads
• Old TRIS Terms: Logarithmic spiral method; Shear failures
• Subject Areas: Highways; Pavements;

Filing Info

• Accession Number: 00205915
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Aug 15 1971 12:00AM