SIMPLE OVERLAY DESIGN METHOD FOR GRAVEL ROADS

A simple method to use deflection measurements for design of overlay thickness on low-volume gravel roads is described. Deflection values are recorded at the center of a circular loading plate and at a certain distance from the center. By using the theory of elasticity, it has been found that a certain arithmetic function of the two deflections measured varies almost linearly with the subgrade modulus within rather wide limits of thickness and elastic modulus of the gravel layer; the relation is nearly independent of these values. This relation has been confirmed by analysis of a large number of measurements made by the falling-weight deflectometer on a number of gravel road sections. Similarly, a relation for determination of the upper layer thickness in a two-layer system has been found. Determination of the design deflection meets with two problems: variation along the road and variation with season. The effect of variation along the road will be solved by using running averages and that of seasonal variations by applying a weighting factor. For simplification of the design procedure, it has been assumed that there is a constant ratio between the subgrade modulus and the modulus of the gravel layer; this assumption has been confirmed by actual measurements. Analysis of the standard designs prescribed by the Swedish Road Specifications on different subgrades at different traffic intensities has shown a unique relation between vertical subgrade stress and traffic intensity at each subgrade type. The required equivalent overlay thickness may therefore easily be selected and the corresponding overlay thickness of different paving materials determined. A discussion follows regarding the practical problems associated with the measurement procedure, such as length of intervals between measurements, magnitude of load applied, nonlinearity of materials, and seasonal variations. (Author)

• Record URL:
  • http://onlinepubs.trb.org/Onlinepubs/trr/1983/898/898-023.pdf
• Record URL:
  • https://scholar.google.com/scholar_lookup?title=SIMPLE+OVERLAY+DESIGN+METHOD+FOR+GRAVEL+ROADS&author=A.+Homsi&publication_year=1983
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/0309035112
• Supplemental Notes:
  • Publication of this paper sponsored by Committee on Low-Volume Roads. 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
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Homsi, Abdullah
• Conference:
  • Third International Conference on Low-Volume Roads
  • Location: Tempe Arizona, United States
  • Date: 1983-7-24 to 1983-7-28
• Publication Date: 1983

Media Info

• Media Type: Print
• Features: Figures; References; Tables;
• Pagination: pp 150-157
• Monograph Title: LOW-VOLUME ROADS: THIRD INTERNATIONAL CONFERENCE, 1983
• Serial:
  • Transportation Research Record
  • Issue Number: 898
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Coefficient of subgrade reaction; Deflection; Design methods; Elasticity (Mechanics); Gravel roads; Low volume roads; Modulus of elasticity; Nonlinear systems; Overlays (Pavements); Seasons; Stresses; Thickness; Traffic flow
• Uncontrolled Terms: Nonlinearity; Seasonal variations
• Old TRIS Terms: Elastic theory
• Subject Areas: Design; Geotechnology; Highways; Pavements; I22: Design of Pavements, Railways and Guideways;

Filing Info

• Accession Number: 00376540
• Record Type: Publication
• ISBN: 0309035112
• Report/Paper Numbers: N908
• Files: TRIS, TRB
• Created Date: Aug 30 1983 12:00AM