Nonlinear pavement foundation modeling for three-dimensional finite-element analysis of flexible pavements

Minkwan Kim, Erol Tutumluer, Jayhyun Kwon

Research output: Contribution to journalArticlepeer-review


Pavement foundation geomaterials, i.e., fine-grained subgrade soils and unbound aggregates used in untreated base/subbase layers, exhibit nonlinear behavior under repeated wheel loads. This nonlinear behavior is commonly characterized by stress-dependent resilient modulus material models that need to be incorporated into finite element (FE) based mechanistic pavement analysis methods to predict more accurately the pavement resilient responses, such as stress, strain, and deformation. Many general-purpose FE programs have been used to predict such pavement responses under various traffic loading conditions while not considering properly material characterizations of the unbound aggregate base/ subbase and subgrade soil layers. This paper describes the recent pavement FE modeling research efforts at the University of Illinois focused on using both the specific-purpose axisymmetric and general-purpose three-dimensional (3D) FE programs for flexible pavement analyses. To properly characterize the resilient behavior of pavement foundations, nonlinear stress-dependent modulus models have been programmed in a user material subroutine (UMAT) in the commercial general-purpose finite-element program ABAQUS. The results indicated that proper characterizations of the nonlinear stress-dependent geomaterials significantly impacted accurate predictions of critical pavement responses. The prediction ability of the developed nonlinear UMAT characterization was next validated by predicting similar pavement critical responses to those measured from field instrumented pavement test sections. Different resilient modulus models, considering both axisymmetric and 3D stress states, developed from true triaxial test data on unbound granular materials were also studied. When the intermediate principal stresses were taken into account in the 3D modulus model development unlike in the axisymmetric models, somewhat lower asphalt concrete tensile strains were obtained from 3D nonlinear FE analyses of flexible pavements with unbound aggregate bases.

Original languageEnglish (US)
Pages (from-to)195-208
Number of pages14
JournalInternational Journal of Geomechanics
Issue number5
StatePublished - 2009


  • Aggregates
  • Finite element method
  • Flexible pavements
  • Nonlinear analysis
  • Stress
  • Subgrades

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Soil Science


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