Quantitative assessment of impact of layer moduli on surface deflections

This paper deals with the interpretation of falling weight deflectometer data, with emphasis being placed on presenting a methodology that can be used to determine the sensitivity of measured deflections to the location and stiffness of each layer in a pavement-subgrade system. The notion of contribution ratio, which is a measure of a layer's contribution to measured displacement, is presented. The methodology applies to both elastostatic and dynamic responses. As a result, the procedure can be used to also identify the significance of loading frequency on the effect that a layer has on measured response. Examples are given to demonstrate the application of contribution ratio, examining the effects of variation in layer moduli, as well as loading history, on measurements.