Numerical simulation of rolling dynamic deflectometer tests

The responses of typical flexible and rigid pavements to the dynamic loads imposed by the rolling dynamic deflectometer (RDD) were investigated. The R DD is a recently developed nondestructive testing vehicle that applies a st eady-state harmonic force while continuously moving along the pavement. To find the pavement response to moving harmonic loads, a numerical method usi ng the elastodynamics solution for stationary impulsive loads applied to la yered media and the superposition of the effect of sequential loading impul ses at different stations (spaced according to the advance velocity of the load) was implemented. The effects of RDD velocity, loading frequency, dept h to bedrock, and layer stiffness on the deflection basins were investigate d in the longitudinal and transverse directions. The results show that for the vehicle velocities and loading frequencies that will be used in conjunc tion with the RDD, dynamic effects caused by the motion of the vehicle are negligible, and the deflection basins at any instant of time essentially ar e the same as those that would be obtained with a stationary static or harm onic load, with the advantage to RDD testing being that the loading magnitu de and loading frequency can be changed easily and that profiling is contin uous along the pavement.