This paper reports studies in which the amount of rutting occurring in the subgrade soil of prototype accelerated-traffic test pavements has been computed, and the rutting characteristics of subgrade soil as related to factors such as pavement thickness, subgrade strength, magnitude of load, and load repetitions have been investigated. Computations wer also made on subgrade soils of many pavements designed by the CBR equation for different loads and different subgrade strengths by using the procedure suggested by Monismith and others. The BISTRO computer program was used to compute the stresses in the subgrade. The test pavements analyzed in this study were conventional flexible pavements and full-depth asphalt pavements. The selections of modulus values for the asphalt concrete, unbound granular materials, and subgrade soils are explained. The study results indicate that the surface rut depth measured at the time the pavement is judged to be failed may increase as the thickness of the pavement is increased, even though the material in each layer of the pavement has been properly selected and compacted. Since the surface rut depth is not limited by the failure criteria, when 2 pavements are designed for the same performance level the surface rut depth and the subgrade rutting will be greater for the thicker pavement, while the elastic vertical strain at the surface of the subgrade will be nearly the same for the 2 pavements. If it is desired that pavements designed for the same performance level have the same degree of rutting in the subgrade, the elastic vertical strains at the subgrade surface induced by the load will have to be varied, with the smaller elastic strains allowed for stronger subgrades.

Media Info

  • Media Type: Print
  • Features: Figures; Photos; References; Tables;
  • Pagination: pp 44-48
  • Monograph Title: Soil mechanics: rutting in asphalt pavements, embankments on varved clays and foundations
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00162997
  • Record Type: Publication
  • ISBN: 0309025958
  • Files: TRIS, TRB
  • Created Date: Oct 13 1996 12:00AM