Calibration of Mechanistic-Empirical Models for Flexible Pavements Using the WesTrack Experiment

摘要

Calibration of Mechanistic-Empirical (ME) models is an integral part of Caltran's commitment to adopting an ME pavement design method. As a first step, 27 flexible pavement accelerated pavement test sections trafficked by the two California Heavy Vehicle Simulators (HVSs) were used to calibrate the ME models of the software tool CalME. This paper deals with the second step, where the 26 original sections from the WesTrack experiment were used for calibration of CalME models.rnMaterial parameters for calibrating the incremental-recursive models were determined from Falling Weight Deflectometer (FWD) tests and from laboratory tests. The results of the WesTrack experiment, in terms of temperatures-at different depths, time of load applications, measured rutting and FWD deflections, and recorded distresses were imported to the CalME database. Each section was then simulated, hour by hour, for the total duration of the experiment. The measured FWD deflections measured at intervals during trafficking at WesTrack were compared to the deflections calculated by CalME, to ensure that the pavement response was predicted reasonably well. The empirical components of the ME models were then calibrated so that the predicted performance would match the measured performance. For prediction of asphalt fatigue a shift factor between laboratory fatigue and in-situ fatigue was determined. For the Fine and Fine Plus mixes the shift factor was found to be approximately 15 (i.e. a load in the laboratory corresponds to 15 loads in-situ) and for the Coarse mix approximately 5, although both values may be somewhat high. For permanent deformation of the asphalt layers the permanent strain determined from Repeated Simple Shear Tests - Constant Height (RSST-CH) in the laboratory should be multiplied by a factor of 90 for Fine and Fine Plus mixes and by 80 for Coarse mixes, to result in the measured downward permanent deformation of the asphalt, in mm. The models used for unbound materials in the HVS experiments were confirmed.