Correction of deflection bowls measured by rolling devices using simple shape function

Abstract

Deflection measurement is one of the most appropriate non-destructive methods for the evaluation of pavement mechanical characteristics. In France, deflectographs and curviameter are used for continuous measurement of deflection bowls. Despite their capacity to perform measurements every 5 meters, they tend to underestimate the measured deflection compared to an anchored displacement sensor, considered as the reference. The measuring principles of these devices introduce several measurement biases. To overcome these issues, a correction process has been developed. The approach consists in simulating the deflection bowl measured under the complete truck, and taking into account the operating principles of the measurement system. The simulation of the deflection bowl under the complete truck is carried out using a simple shape function of a deflection bowl under a single wheel defined by Jouve and Martinez and the principle of load superposition. An optimization process minimizes the difference between the simulated and measured deflection bowl. Once the parameters of this model are determined, a “corrected” deflection bowl, independent of the measurement device, is calculated. The proposed correction method is validated by a full scale trial, comparing Curviameter measurements with reference deflection values.

Keywords

• Pavement survey
• Deflection measurement
• Curviameter
• Jouve and Martinez model
• Optimization
• Measurement correction process