As mechanistic-empirical (M-E) design continues to advance toward full implementation by state agencies, there is a need to assess the accuracy of the load-response models under dynamic truck loading. The load response model is a core component of flexible pavement M-E design and the common practice is to use a layered elastic approach to predict pavement responses under load. Concerns regarding accuracy of this type of model arise when considering unbound materials exhibiting non-linear behavior, viscoelastic hot-mix asphalt (HMA) materials and dynamic loads applied by moving traffic. Despite this, layered elastic models continue to be the state-of-the practice for most pavement design and analysis applications. The objective of this study was to assess the accuracy of a layered elastic model with respect to measured pavement responses under live traffic. Specifically, eight test sections at the National Center for Asphalt Technology (NCAT) Test Track were instrumented to measure vertical pressures in the unbound base and subgrade layers. The test sections consisted of various HMA thicknesses and used modified and unmodified asphalt binders. Material properties were established using backcalculation of falling weight deflectometer (FWD) data. The test sections were then simulated with the layered elastic computer program, WESLEA. The simulations also included actual loading configurations applied by the tractor-triple and single trailer vehicles used at the Test Track. The study focused on in-tact pavements (i.e., no cracking) and comparisons between theoretical and measured pavement responses were made over a wide range of environmental conditions and the two different truck load configurations. A unique approach was developed to account for the natural wander of the vehicles relative to the fixed location of the pressure gauges. The measured responses were generally within 15 percent of theoretical with a strong correlation between the two sets of data (R2 > 0.80). In general, the results from layered elastic back and forward-calculation compared well with measured pavement responses obtained from the NCAT Test Track data. At higher pressures, which are resulting from higher pavement temperature, some deviations were observed between predicted and measured responses in this study.
Measured and Theoretical Pressures in Base and Subgrade Layers under Dynamic Truck Loading
Airfield and Highway Pavements Specialty Conference 2006 ; 2006 ; Atlanta, Georgia, United States
Airfield and Highway Pavement ; 155-166
2006-04-28
Conference paper
Electronic Resource
English
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