Mechanistic Evaluation and Calibration of the AASHTO Design Equations andMechanistic Analysis of the SHRP Asphalt Surfaced Pavement Sections

摘要

Mechanistic evaluation of the AASHTO flexible design equations was conducted byusing 243 artificial pavement sections with various layer properties, roadbed soil modulus, and traffic volumes. Throughout the analyses it is assumed that the mechanistic responses (stresses, strains, and deflections) of the pavement sections due to an applied 9,000-pound of load are indicative of the level of damage delivered to these sections. Results of the analyses indicated that while the AASHTO design method produces pavement sections with an almost equal level of protection, the damage delivered to the various layers vary from one section to another. It is also shown that the AASHTO method does not consistently account for the effects of the drainage quality (drainage coefficient) on the layer thicknesses and/or on the pavement responses. A mechanistic-based modification procedure of the effects of the AASHTO drainage coefficient is presented. It is shown that the mechanistic-based method produces more consistent pavement sections and that the variations of their mechanistic responses are much less than those produced by the AASHTO method. Further, a nomograph for estimating the effects of drainage coefficients on the expected life of the pavement structures is also presented and discussed. (Copyright (c) 1994 National Academy of Sciences.)