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Title: Evaluation of nonlinear resilient moduli of unbound granular materials from accelerated traffic test data
Authors: United States. Federal Aviation Administration.
Chou, Yu T.
Keywords: Finite element method
Stress-strain relations
Flexible pavements
Traffic tests
Granular materials
Publisher: Soils and Pavements Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Technical Report
Abstract: A method for evaluating the resilient moduli of unbound granular materials is presented herein. The moduli were back-calculated from correlations of performance data of numerous full-scale accelerated traffic test pavements with computed critical stresses and strains of test pavements. The test pavements consisted of conventional flexible pavements as well as all-bituminous concrete (ABC) pavements. The loadings include single and multiple wheels. The stresses and strains in the pavement structures were computed by the finite element technique incorporated with the tried nonlinear stress-strain relations of pavement materials. A general discussion on the nonlinear characteristics of pavement materials and limitations of the finite element computer program is presented. The parameters used to establish the correlations included (A.) radial tensile strains at the bottom of the ABC, (B.) maximum radial tensile strains and minimum ratios of radial tensile stress to vertical stress in the unbound granular layers, and (C.) vertical strains at the subgrade surface. Parameter B was developed only for single-wheel loads. The principle of superposition was used in the computations for multiple-wheel load assemblies. In Appendix A, stresses and deflections computed by the nonlinear-finite element method as compared with actual measurements of stress and deflection for a full-scale flexible test pavement are given. The nonlinear resilient moduli used in the computations were evaluated from traffic test data presented in this report. The nonlinear characteristics of pavement materials under loads are discussed. It is recommended that the nonlinear resilient moduli presented in the report be used to compute pavement responses when laboratory repeated load test data on granular materials are not available.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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