COMPRESSIVE STRESS PULSE TIMES IN FLEXIBLE PAVEMENTS FOR USE IN DYNAMIC TESTING

TRAFFIC MOVING OVER A PAVEMENT STRUCTURE RESULTS IN A LARGE NUMBER OF RAPIDLY APPLIED STRESS PULSES BEING APPLIED TO THE MATERIAL COMPRISING EACH LAYER. THIS CONDITION IS BEST CHARACTERIZED BY DYNAMIC TESTS SUCH AS THE REPEATED LOAD TRIAXIAL TEST OR FATIGUE TESTS. THE SHAPE AND DURATION OF THE COMPRESSIVE STRESS PULSE RESULTING AT DIFFERENT DEPTHS BENEATH THE SURFACE ARE STUDIED FOR SEVERAL FLEXIBLE PAVEMENT SYSTEMS AND VEHICLE SPEEDS VARYING BETWEEN 1 AND 45 MPH. A COMPARISON IS MADE OF THE COMPRESSIVE STRESS PULSES CAUSED BY A VEHICLE MOVING OVER A LAYERED PAVEMENT SYSTEM AT A SPEED OF 1 MPH USING BOTH LINEAR AND NONLINEAR ELASTIC FINITE ELEMENT THEORY. VISCOUS EFFECTS AND INERTIA FORCES ARE NEGLECTED. BECAUSE THE NORMALIZED STRESS PULSES CALCULATED USING THE LINEAR ELASTIC THEORY ARE FOUND TO AGREE CLOSELY WITH THOSE CALCULATED USING THE NONLINEAR THEORY, LINEAR ELASTIC FINITE ELEMENT THEORY IS USED THROUGHOUT THE STUDY. THE RESULTS SHOW THAT THE SHAPE OF THE COMPRESSIVE STRESS PULSE VARIES FROM APPROXIMATELY A SINUSOIDAL ONE AT THE SURFACE TO MORE NEARLY A TRIANGULAR PULSE AT DEPTHS BELOW APPROXIMATELY THE MIDDLE OF THE BASE. TYPICALLY, THE COMPRESSIVE PULSE TIME ALSO VARIES ALMOST INVERSELY WITH VEHICLE SPEED UP TO AT LEAST A SPEED OF 45 MPH, THE CALCULATED STRESS PULSE TIMES WERE EMPIRICALLY CORRECTED FOR VISCOUS EFFECTS AND INERTIA FORCES USING THE RESULTS OF FIELD MEASUREMENTS MADE AT THE AASHO ROAD TEST. CURVES ARE PRESENTED FROM WHICH APPROXIMATE COMPRESSIVE STRESS PULSE TIMES CAN BE SELECTED FOR USE IN DYNAMIC TESTING. /AUTHOR/

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/hrr/1971/345/345-003.pdf
• Supplemental Notes:
  • Sponsored by Committee on Strength and Deformation Characteristics of Pavement Sections and presented at the 50th Annual Meeting. 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:
  • Barksdale, Richard D
• Publication Date: 1971

Media Info

• Media Type: Print
• Features: Figures; References;
• Pagination: pp 32-44
• Monograph Title: Highway soils engineering
• Serial:
  • Highway Research Record
  • Issue Number: 345
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Compression; Dynamic tests; Elasticity (Mechanics); Finite element method; Flexible pavements; Linearity; Pulse modulation; Speed; Stresses; Vehicles
• Old TRIS Terms: Elastic theory; Finite elements; Layered system mechanics; Pulse time modulation
• Subject Areas: Highways; Pavements; Vehicles and Equipment;

Filing Info

• Accession Number: 00205933
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Sep 13 1971 12:00AM