Enhanced Analysis of Falling Weight Deflectometer Data for Use With Mechanistic-Empirical Flexible Pavement Design and Analysis and Recommendations for Improvements to Falling Weight Deflectometers

2017Sivaneswaran, NadarajahDistribution number: HRDI-20/03-17(WEB)EPDFTech ReportFHWA-HRT-15-063DTFH61-11-C-00026Falling weight deflectometersMechanistic-empirical pavement designPavement management systemsTime domain analysisViscoelastic materialsUnited StatesUnited States. Federal Highway AdministrationChatti, KarimKutay, Muhammed EminLajnef, NizarZaabar, ImenVarma, SudhirLee, Hyung SukMichigan State UniversityUnited States. Federal Highway Administration. Office of Acquisition ManagementSivaneswaran, NadarajahFederal Highway AdministrationThis report describes the efforts undertaken to review the status of falling weight deflectometer (FWD) equipment, data collection, analysis, and interpretation, including dynamic backcalculation, as they relate to the models and procedures incorporated in the Mechanistic-Empirical Pavement Design Guide. The work conducted in this project resulted in the following: (1) Development of a backcalculation scheme (BACKLAVA) in the time domain using a quasi-static model (LAVA) as its forward solution and genetic algorithm (GA) as its search engine. BACKLAVA is a backcalculation algorithm for a constant asphalt concrete (AC) layer temperature. (2) Development of a backcalculation scheme (BACKLAVAP) in the time domain using a quasi-static model (LAVAP) as its forward solution and GA as its search engine. BACKLAVAP is a backcalculation algorithm for a temperature profile in an AC layer. (3) Development of a backcalculation scheme (BACKLAVAN) in the time domain using a quasi-static model (LAVAN) as its forward solution and GA as its search engine. BACKLAVAN is a backcalculation algorithm for a viscoelastic AC layer and a nonlinear base layer. (4) Development of a backcalculation scheme (DYNABACK-VE) in the time domain using a time-domain viscoelastic dynamic model (ViscoWave-II) as its forward solution and a hybrid approach (GA and Levenberg-Marquardt algorithm) as its search engine. DYNABACK-VE is a backcalculation algorithm for a viscoelastic AC layer with temperature profile and linear unbound layers. (5) Short list of recommendations for FWD equipment enhancements. The tools developed in this project are standalone applications that could be used on most computers.74