Simulation of Lightweight Deflectometer Measurements Considering Nonlinear Behavior of Geomaterials

Abstract

Lightweight deflectometers (LWDs) are being used more often for modulus-based quality control of earthwork. One of the practical concerns about implementation of LWDs is that the equation used to estimate the LWD modulus is based on elastic half-space theory and does not account for the nonlinear behavior of soil and soil–impact plate interaction. The finite element method can be used to study the effects of nonlinear behaviors of geomaterials and the soil–plate interaction on the measured deflections. This study provides a means for accounting for the impact of these parameters on the measured responses and the depths of influence. A dynamic finite element model that considers the nonlinear behavior of geomaterials was developed to simulate the LWD on a pavement structure. A comprehensive range of single-layer and two-layer systems with a wide range of properties and thicknesses was considered. Transfer functions were developed to adjust the surface deformations and moduli from the responses obtained from a simple layered elastic static model. The study provides practical relationships that minimize the additional effort in implementing time-consuming dynamic finite element methods. The relationships proposed in this study can be used to estimate more representative target LWD modulus values.