THE BEHAVIOR OF FLEXIBLE PAVEMENTS UNDER MOVING WHEEL LOADS

THE ABILITY TO PREDICT THE PATTERN OF TRANSIENT STRESS- DEFORMATION BEHAVIOUR OF A ROAD UNDER MOVING WHEEL LOADS, WHICH IS A NECESSARY STEP TO DEVELOPING A RATIONAL METHOD OF PAVEMENT DESIGN REQUIRES SIMPLIFYING ASSUMPTIONS TO BE MADE REGARDING THE LOADING CONDITIONS, INTERFACIAL CONTACT BETWEEN LAYERS AND THE UNIFORMITY AND RHEOLOGICAL PROPERTIES OF THE MATERIALS IN THE ROAD. CONVENIENT EMPIRICAL FORMULAE HAVE BEEN DEVELOPED FOR SOME COMPONENTS OF INTERFACIAL STRESS AND SURFACE DEFLECTIONS FOR TWO AND THREE LAYER ELASTIC SYSTEMS. THESE HAVE BEEN USED TO EXAMINE THE ERRORS ARISING FROM DIFFERENCES BETWEEN REAL AND ASSUMED CONDITIONS IN THE SHAPE OF THE TYRE CONTACT AREA AND THE DISTRIBUTION OF STRESS ON THE ROAD SURFACE. FOR THE TYRES EXAMINED THE ASSUMPTION OF A CIRCULAR LOADED AREA DEFINED BY THE WHEEL LOAD DIVIDED BY THE INFLATION PRESSURE WAS FOUND TO BE A SATISFACTORY APPROXIMATION IN THE ELASTIC ANALYSIS. DYNAMIC LOADING EFFECTS GENERATED BY VERTICAL MOTION OF THE WHEEL PASSING OVER SURFACE IRREGULARITIES HAS BEEN SHOWN TO PRODUCE UP TO 35 PER CENT HIGHER /OR LOWER/ SURFACE LOADS THAN THE NOMINAL /STATIC/ WHEEL LOAD ON EXPERIMENTAL SECTIONS OF POOR RIDING QUALITY FROM AN UNLADEN TEST VEHICLE TRAVELLING AT 15 M.P.H. IN ADDITION, VARIATIONS OF UP TO 40 PER CENT WERE RECORDED IN THE VERTICAL COMPONENT OF STRESS IN THE SUBGRADE BENEATH THE SAME TYPE OF CONSTRUCTION ATTRIBUTABLE TO VARIATIONS OF NOMINALLY THE SAME MATERIALS; THE LARGEST VARIATIONS WERE OBSERVED BENEATH A CRUSHED STONE BASE AND THE SMALLEST BENEATH UNCRACKED CEMENT-BOUND BASES. THE EFFECTS OF DYNAMIC LOADING AND VARIABILITY OF MATERIALS ARE USUALLY INTER-RELATED, AND SUGGESTIONS ARE MADE FOR FURTHER STUDIES UNDER NORMAL TRAFFIC CONDITIONS. DIFFICULTIES OF DEFINING THE APPROPRIATE ELASTIC MODULI OF SOILS, UNBOUND MATERIALS AND BITUMINOUS MATERIALS FOR USE IN THE ELASTIC ANALYSIS ARE DISCUSSED. COMPARISONS ARE MADE OF THE MEASURED VALUES OF THE SURFACE DEFLECTION AND THE VERTICAL COMPONENT OF STRESS IN THE SOIL WITH THOSE CALCULATED USING MODULI DEDUCED FROM VIBRATIONAL EXPERIMENTS. SUGGESTIONS ARE MADE FOR FURTHER EXPERIMENTAL WORK TO REMOVE SOME OF THE PRESENT UNCERTAINTIES. /AUTHOR/

• Supplemental Notes:
  • Preprint VoL, PP 854-871, 12 FIG, 4 TAB, 20 REF
• Authors:
  • Lister, N W
  • Jones, R
• Conference:
  • Intl Conf Struct Design Asphalt Pvmts
• Publication Date: 1967-1

Subject/Index Terms

• TRT Terms: Deflection; Deformation curve; Dynamic loads; Flexible pavements; Materials; Modulus of elasticity; Motion; Motor vehicles; Pavement design; Pavements; Performance; Rheology; Viscoelastic materials; Viscoelasticity; Wheel loads
• Uncontrolled Terms: Moving vehicles
• Old TRIS Terms: Circular loaded areas; Pavement deflection
• Subject Areas: Highways; Materials; Pavements;

Filing Info

• Accession Number: 00206662
• Record Type: Publication
• Files: TRIS
• Created Date: Aug 1 1994 12:00AM