Forward and inverse models for parameter identification of layered media

This article presents a newly developed parameter identification procedure for layered media and in particular for pavement structures via the use of the Falling Weight Deflectometer (FWD) test. Emphasis is placed on the advantages of the procedure over currently used methods. The procedure involves the development of both forward and inverse models. The spectral element technique is utilized. The spectral element contributes to the efficiency of the procedure because of its ability to describe a whole material layer by one element, thus rendering the size of the system of equations very small. Also, the derivation of the element stiffness matrix leads naturally to the formulation of the analytical objective function of the system, which can be solved by general-purpose minimization techniques. Three case studies are examined, which address utilization of the procedure for FWD data harmonization, its accuracy, and its robustness.