Abstract:
IN THE EXPERIMENTS IT APPEARED THAT BOTH THE MAGNITUDE AND THE PATTERN OF DISTRIBUTION OF PRESSURES ON THE EXPERIMENTAL DRY SUBGRADE WERE INDEPENDENT OF THE INFLATION PRESSURE OF THE TIRE THROUGH WHICH THE LOADS WERE APPLIED TO THE FLEXIBLE PAVEMENTS. FOR A GIVEN THICKNESS OF PAVEMENT AND A GIVEN LOAD, THE PATTERN OF PRESSURE DISTRIBUTION ON THE SUBGRADE AND THE MAXIMUM PRESSURE DIRECTLY UNDER THE LOAD WERE UNCHANGED WHEN THE INFLATION PRESSURE OF THE TIRE WAS VARIED FROM 30 LB. PER SQ. IN. TO 70 LB. PER SQ. IN. ALSO, IN THE CASE OF THE THINNER PAVEMENTS, HIGHER LOADS, AND LOWER INFLATION PRESSURES, IT WAS NOT UNCOMMON TO MEASURE UNIT PRESSURES ON THE SUBGRADE WHICH WERE CONSIDERABLY IN EXCESS OF THE INFLATION PRESSURE OF THE TIRE. WHEN THE INTERNAL PRESSURE OF THE TIRE WAS INCREASED TO 70 LB. PER SQ. IN. FOR SUBSEQUENT LOAD APPLICATIONS THE CONTACT AREA WAS REDUCED TO 55.3 SQ. IN., BUT THE MAXIMUM PRESSURE ON THE SUBGRADE AND THE PATTERN OF DISTRIBUTION WERE UNCHANGED. THE MAXIMUM PRESSURE ON A DRY SUBGRADE PRIOR TO FAILURE OF THE 4 1/2 IN. SAND-CLAY BASE COURSE MAY BE AS MUCH AS NINE TIMES GREATER THAN THE MAXIMUM PRESSURE ON A WET SUBGRADE. /AUTHOR/
Supplemental Notes:
Vol 21, pp 110-117, 6 FIG, 1 TAB, 7 REF; part of Report of Committee on Flexible Type Pavements. 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.
