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The results of backcalculation using field test data were compared with the results obtained using WESDEF. For the theoretical deflection basins, the results of backcalculation were compared with actual elastic parameters, and excellent agreement was observed. The method was verified by theoretically generated deflection profiles and falling weight deflectometer data measurements conducted at Edmonton Municipal Airport, Canada. The neural networks are trained to find moduli of elasticity of the constructed layers and a coefficient of sub-grade reaction to accurately match a measured deflection profile. The constructed layers are modeled as compressible elastic layers, whereas the subgrade is modeled as a Winkler foundation. N2 - A neural-network-based backcalculation procedure is developed for multilayer composite pavement systems.
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T2 - Neural-network-based backcalculation program for composite pavements The backcalculation procedure is implemented in a computer program called DIPLOBACK.", Similar trends were observed for elastic parameters of all the pavement layers.
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The backcalculation procedure is implemented in a computer program called DIPLOBACK.Ībstract = "A neural-network-based backcalculation procedure is developed for multilayer composite pavement systems. EVERCALC uses RMSE.A neural-network-based backcalculation procedure is developed for multilayer composite pavement systems. In backcalculating layer moduli, the measure of how well the calculated deflection basin matches (or converges to) the measured deflection basin was previously described as the “error check.” This is also referred to as the “goodness of fit” or “convergence error.” The primary measure of convergence is typically Root Mean Square (RMS) or Root Mean Square Error (RMSE).
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Backcalculation Flowchart Measure of Convergence In some backcalculation programs, a range (minimum and maximum) of moduli are selected or calculated to prevent program convergence to unreasonable moduli levels (either high or low).įigure 1. Various methods have been employed within the various backcalculation programs to converge on a set of layer moduli which produces an acceptable error between the measured and calculated deflection basins. There are various error measures which can be used to make such comparisons (more on this in a subsequent paragraph in this section). This element simply compares the measured and calculated basins. Layered elastic computer programs are generally used to calculate a deflection basin. These moduli are usually estimated from user experience or various equations. The seed moduli are the initial moduli used in the computer program to calculate surface deflections. Includes all layer thicknesses and load levels for a specific test location. Includes the measured pavement surface deflections and associated distances from the load.