Accurate measurement of pavement deflection velocity under dynamic loads

Abstract Bearing capacity is one of the most important indices that reflects the condition of road pavements. For high-speed and non-destructive measurement of bearing-capacity values, advanced dynamic deflectometers have been developed in the past decade. The deflection range is typically computed based on the Euler-Bernoulli elastic equation with a number of deflection velocity values. The deflection velocity refers to the vertical velocity of pavement deflection under a force action; it can be captured by a number of positions in the deflection basin by laser Doppler sensors. Thus, the accurate measurement of deflection velocity is of vital importance to the performance of a deflectometer system. In this paper, we consider the problem of accurately measuring the deflection velocity based on dynamic posture and calibration. Both methods build the relationship between the measured values and the relative postures of the sensors and targets. We first validate the effectiveness of the static calibration that determines the relative postures of the sensors with indoor settings. Second, with respect to self-correlation of the velocity values, the dynamic-posture-based method and the calibration-based method are compared. Third, the impact of traffic speed on the measuring results is investigated. Last, we further validate the accuracy of the measured velocity by computing deflection ranges and comparing them to ground-truth values. Experiments in real measuring tasks demonstrated that both the calibration-based method and the dynamic-posture-based method can produce accurate and effective results.