WHEEL LOAD STRESS DISTRIBUTION THROUGH FLEXIBLE TYPE PAVEMENTS

THE OBJECT OF THE LABORATORY EXPERIMENTS DESCRIBED HEREIN IS TO PROVIDE BASIC KNOWLEDGE CONCERNING THE MAGNITUDE AND DISTRIBUTION OF THE VERTICAL PRESSURES ON A SUBGRADE BENEATH A FLEXIBLE OR NON-RIGID TYPE OF PAVEMENT WHEN CONCENTRATED LOADS, SUCH AS TRUCK WHEELS, ARE APPLIED TO THE PAVEMENT SURFACE. A SYNTHETIC SUBGRADE OF DRY CLAY LOAM SOIL WAS CONSTRUCTED WITHIN A CONCRETE BIN 8 FT. SQ. IN. PLAN AND ABOUT 2.5 FEET DEEP. FLEXIBLE-TYPE PAVEMENTS WERE CONSTRUCTED ON THIS SUBGRADE OF TWO KINDS OF MATERIALS; ONE A STABILIZED GRAVEL MIXTURE AND THE OTHER A SAND-CLAY MIXTURE. THE THICKNESS OF THESE PAVEMENTS RANGED FROM 3 IN. TO 10 IN. LOADS WERE APPLIED TO THE SURFACE OF THE PAVEMENT AT THE CENTER OF THE 8 FT SQ AREA THROUGH A 7 BY 21, 6-PLY TIRE IN AMOUNTS RANGING FROM 1000 LB. TO 5000 LB. BY 1000 LB. INCREMENTS AND WITH THE TIRE INFLATED TO VARIOUS INTERNAL PRESSURES FROM 30 P.S.I. TO 70 P.S.I. BY 10 LB. OR 20 LB. INCREMENTS. THE VERTICAL PRESSURES ON THE SUBGRADE WERE MEASURED BY MEANS OF SMALL CARBON DISK PILES ARRANGED AT FREQUENT INTERVALS ALONG ELEMENTS PARALLEL TO THE MAJOR AND MINOR AXES OF THE TIRE CONTACT AREA. IN ADDITION TO THE SUBGRADE PRESSURE MEASUREMENTS, AN EXTENSIVE STUDY WAS MADE OF THE RELATION BETWEEN THE CONTACT AREA BETWEEN THE TIRE AND THE PAVEMENT SURFACE AND THE LOAD ON THE TIRE AND THE TIRE INFLATION PRESSURE. THE DATA TAKEN INDICATE THAT, IN THESE EXPERIMENTS, THE SUBGRADE PRESSURE IS DISTRIBUTED IN ACCORDANCE WITH THE TYPICAL HELMET-SHAPED SURFACE OF THE CLASSICAL BOUSSINESQ SOLUTION; THAT THE MAXIMUM PRESSURE OCCURS ON A SMALL AREA OF THE SUBGRADE DIRECTLY BENEATH THE LOAD; THAT THE MAGNITUDE OF THIS PRESSURE MAXIMUM IS INDEPENDENT OF THE TIRE INFLATION PRESSURE, NEARLY DIRECTLY DEPENDENT UPON THE APPLIED LOAD, AND INVERSELY PROPORTIONAL TO THE THICKNESS OF THE PAVEMENT; AND THAT THE LOAD- INFLATION PRESSURE QUOTIENT IS NOT A VALID CRITERION FOR DETERMINING THE AREA OF CONTACT BETWEEN A TRUCK TIRE AND A FLEXIBLE PAVEMENT. /AUTHOR/

• Record URL:
  https://onlinepubs.trb.org/Onlinepubs/hrbproceedings/20/20-011.pdf
• Supplemental Notes:
  • Vol 20, pp 235 - 257, 25 FIG, 2 TAB, 19 REF. 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:
  • Spangler, M G
  • Ustrud, H O
• Publication Date: 1941

Media Info

• Media Type: Digital/other
• Monograph Title: Proceedings of the Twentieth Annual Meeting of the Highway Research Board Held at Washington, D.C. December 3-6, 1940
• Serial:
  • Highway Research Board Proceedings
  • Volume: 20
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Deformation curve; Flexible pavements; Laboratory tests; Pavements; Pressure; Subgrade (Pavements); Thickness; Wheel loads
• Uncontrolled Terms: Contact area; Pavement thickness; Wheel load distribution
• Old TRIS Terms: Circular loaded areas
• Subject Areas: Geotechnology; Highways; Pavements;

Filing Info

• Accession Number: 00207267
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Aug 15 1971 12:00AM