Mechanistic-Empirical Modeling and Design Model Development for Geosynthetic Reinforced Flexible Pavements

823226https://doi.org/10.21949/15184032001Final ReportAdditional and training resources can be access from: https://www.mdt.mt.gov/research/projects/grfp.shtmlPDFTech Reporthttps://ntlrepository.blob.core.windows.net/lib/24000/24700/24763/MT_99160_appendixc.pdfFHWA/MT-01-002/99160-1A99160AggregatesAsphalt concrete pavementsBase course (Pavements)BenefitsFinite element methodFlexible pavementsGeosyntheticsNumerical analysisPavement designPavement layersPavement performanceReinforcement (Engineering)Repeated loadsSubgrade (Pavements)CalibrationEmpirical methodsLinear elasticityMathematical modelsMechanistic designPavement distressStressesMontanaMontana. Dept. of Transportation. Research Section.Perkins, Steven W.Montana State University (Bozeman, Mont.). Department of Civil EngineeringMontana. Dept. of Transportation. Research SectionUnited States. Federal Highway AdministrationUS Transportation CollectionResearch over the past 20 years has demonstrated the benefit provided by geosynthetics when placed within or at the bottom of base aggregate layers in flexible pavement systems for the purpose of reinforcement. Previous experimental work involving the construction and loading of reinforced pavement test sections has demonstrated that values of benefit are strongly dependent on pavement design parameters such as thickness of the structural section and/or stiffness of the subgrade, and properties and type of geosynthetic used. A NCHRP Synthesis (Christopher et al., 2001), provides a survey of geosynthetic base reinforcement usage amongst all U.S. State transportation agencies. The survey found that the primary reasons for lack of usage were the absence of a suitable design method for defining reinforcement benefit and the corresponding inability to define cost-benefit for reinforced pavement systems. This current project was undertaken to provide an analytically based method for the determination of reinforcement benefit. The method developed is expressed solely in terms of design equations used to calculate reinforcement benefit in terms of pavement structural thickness, subgrade strength and several properties related to the geosynthetic. The finite element model developed involves elastic-plastic material models for the asphalt concrete, base aggregate and subgrade layers, and an anisotropic linear elastic model for the geosynthetic. Empirical distress models were developed to relate stress and strain response measures from the finite element model to pavement performance and ultimately reinforcement benefit. Three classes of finite element (FE) response models were developed. The first was for an unreinforced pavement cross-section. The second was one in which reinforcement was modeled by preventing all lateral motion of the bottom of the base aggregate. The influence of geosynthetic properties was evaluated by creating a third class of FE model. In this model, the geosynthetic was explicitly accounted for by including a geosynthetic sheet, modeled with membrane elements, between the base aggregate and subgrade layer. This report provides a detailed description of the finite element response model, the material models used in the FE model, calibration of the material models and how these models relate to commonly used pavement layer material models, and the steps followed to develop the design model.This record also contains the DARWin OUTPUT appendix.90