ABSTRACT
Falling Weight Deflectometer (FWD) has been routinely used to determine the in-situ stiffness of pavement layers. However, FWD is not viewed as a useful tool in pavement failure investigations where shear strength parameters (c and ϕ) of unbound layers, particularly subgrade, are required for the evaluation of shear failure in subgrade layer under moving superheavy load. In this study, a novel FWD-based methodology for estimating the shear strength parameters of the subgrade layer was investigated. To validate the proposed methodology for different types of pavement structures, large-scale experiments have been carried out on a variety of unpaved and paved pavement structures at University of Nevada, Reno. It was found that the FWD surface measurements at multiple load levels in conjunction with the fitting of hyperbolic stress-strain relationship can be used to extend the data obtained at FWD stress levels to the failure state, facilitating a reasonable estimate of the subgrade’s shear strength parameters.
