Diagnostic analysis of dynamic deflection for cracked asphalt pavements under FWD impulsive loading

The falling weight deflectometer (FWD) is a non-destructive testing technology used to calculate the stiffness-related parameters of pavement structures and has been widely used in the pavement engineering field. Deflection basin testing data have an obviously affecting effect on the modulus backcalculation of an asphalt pavement. Identifying effective data of dynamic deflection basins is an important task to perform modulus backcalculation. The objective of this paper is to study the distribution features of dynamic deflection basins of cracked asphalt pavements using a three dimension dynamic finite element method. Based on the systematic analysis, the criteria used to filter effective data of FWD deflection basins were presented and verified with an in-situ case study. The study results demonstrated that the crack width of 0.2 mm was a critical value to determine the existence of contact behavior between vertical crack surfaces. The distribution characteristics of dynamic deflection basins showed a significant difference between intact and cracked pavements. The established criteria, involving surface deflection indicator and surface modulus indicator, were verified to be reasonable and viable for filtering the FWD testing data.