Applicability of Static and Dynamic Analytical Methods to Structural Evaluation of Flexible Pavements Using FWD Data

Abstract

We have two methods to evaluate pavement structures by back-calculation based on linear elastic theory using Falling Weight Deflectometer (FWD) data. One is the multi-layer elastic method (static method), in which the peak load and peak surface deflections at sensors extracted from time-historical FWD data are utilized. The other is the dynamic FEM (dynamic method) directly using the time-historical FWD data for analysis. In this study, back-calculations of layer elastic moduli for the structural evaluation were conducted by static and dynamic methods on FWD data at a flexible pavement, which Transportation Research Board (TRB) has uploaded on the website. At the same time, Dynamic Cone Penetorometer (DCP) and Multi-Depth Deflectometer (MDD) were also performed besides FWD test. The modulus of base layer back-calculated by static and dynamic methods is in good agreement with those estimated by DCP. The modulus of subgrade back-calculated by static method was slightly less than that back-calculated by dynamic method or estimated by DCP. On the other hand, the internal displacements calculated by both static and dynamic methods with back-calculated layer modulus were consistent with the measured results by MDD. Therefore, it was demonstrated that both static and dynamic methods would be applicable to predict the pavement response (displacements) in adequate accuracy