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Title:Permanent Deformation Behavior of Airport Flexible Pavement Base and Subbase Courses
Author(s):Kim, in Tai
Doctoral Committee Chair(s):Tutumluer, Erol
Department / Program:Civil Engineering
Discipline:Civil Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Engineering, Civil
Abstract:After the first round of testing at the Federal Aviation Administration's (FAA's) National Airport Pavement Test Facility (NAPTF) was completed, significant rutting was found to take place in the flexible pavement test sections in the granular base and subbase layers, designated as NAPTF P209/P154 base and subbase according to FAA's construction specifications. To account for the rutting performances of these substantially thick granular layers, a comprehensive set of repeated load triaxial tests, considering both constant and variable confining pressure (CCP and VCP) conditions, were conducted on the NAPTF P209 base and NAPTF P154 subbase granular materials. Based on the laboratory test results, both CCP and VCP type permanent deformation models were developed to predict maximum ruts occurred at the NAPTF under both 6-wheel and 4-wheel gear loadings applied following a wander pattern. Realistic pavement stresses induced by moving wheel loads were examined in the unbound aggregate base and subbase layers and the important effects of rotation of principal stress axes were indicated for a proper characterization of the permanent deformation behavior. Triaxial test data were obtained and analyzed from testing aggregates under various realistic in-situ stress paths due to moving wheel loading. Permanent deformation characterization models were then developed based on the experimental test data to include the static and dynamic stress states and the slope of stress path loading. The models that also considered the stress path slope variations predicted best the stress path dependency of permanent deformation accumulation. The developed rutting models were first calibrated for the field conditions and then evaluated for predicting the field accumulation of permanent deformations by properly taking into account the NAPTF trafficking data, effects of stress rotation due to moving wheel loads, and loading stress history effects. A comparison of the measured and predicted permanent deformations indicated that a good match for the measured rut magnitudes and the accumulation rates could only be achieved when the magnitudes and variations of stress states in the granular layers, number of load applications, gear load wander patterns, previous loading stress history effects, trafficking speed or loading rate effects, and finally, principal stress rotation effects due to moving wheel loads were properly accounted for in the laboratory testing and permanent deformation model development. In addition, multiple stress path tests conducted to simulate the extension-compression-extension type rotating stress states under a wheel pass gave much higher permanent strains than those of the compression only single path tests. Finally, a new test procedure was proposed to account for rutting potentials of granular materials.
Issue Date:2005
Description:310 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2005.
Other Identifier(s):(MiAaPQ)AAI3199046
Date Available in IDEALS:2015-09-25
Date Deposited:2005

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