ABSTRACT
Continuous deflection measurements are gaining increased interest due to the benefit of effectively measuring large networks. However, a pavement responds differently to a continuously moving load than to an impulse load from a Falling Weight Deflectometer (FWD) which has been the industry standard for structural testing for decades. Several approaches have been taken to assess the level of agreement between the two types of deflection measurement devices. This is important for road authorities for which deflection measurements provide a basis for maintenance decisions.
This paper presents a viscoelastic and dynamic model able to simulate both a moving wheel and an impulse load, and hence generate a link between continuous deflection devices and FWD. The model can be used to perform backcalculation of continuous deflection measurements to obtain pavement properties. These properties are then used as input to the model to simulate an FWD experiment. The output is FWD deflections corresponding to what an FWD would have measured at the place where the continuous deflection measurements were reported. This procedure is applied to RAPTOR measurements collected at a city road in Copenhagen, Denmark. The calculated corresponding FWD deflections were compared with actual FWD measurements collected on the same day. The results show a good agreement of the center deflection, but also outer deflections agree well. The viscoelastic properties obtained in the backcalculation of RAPTOR measurements were in good agreement with the FWD deflection time histories.
