Structural Evaluation of Pavement by Backcalculation

A new method of structural evaluation (W-BALM) has been developed using the histories of impulsive force and surface deflections measured by falling weight deflectometers (FWD). It is assumed that pavement is composed of a multilayered half-space with Voigt type material characteristics. Surface deflections are obtained by analytically solving a wave propagation problem using Hankel transformation and fast Fourier transform (FFT). Voigt model parameters of pavement layers are determined such that computed surface deflections coincide with measured by using the Gauss-Newton method. The results are compared with those from BALM (static Back Analysis for Layer Moduli) and those from D-BALM (Dynamic Back Analysis for Layer Moduli). It is found that W-BALM and D-BALM yield similar results but differ from the results of BALM.