Measurement Accuracy Analysis of Distributed Fiber Optic Sensors for Asphalt Mixture Based on the DEM-FDM Coupled Method

Distributed fiber optic sensors (DFOSs) have been effectively used for pavement health monitoring. However, the inhomogeneity of the asphalt mixture and the characteristics of the sensor affect the measurement accuracy, which in turn affects the performance evaluation of asphalt pavement. In this study, the strain of nonembedded DFOS specimens was used as a reference and compared with the strain of embedded DFOS specimens to analyze the accuracy of DFOS based on the four-point bending test. To further improve accuracy, a numerical simulation model was established by coupling the discrete element method (DEM) and the finite difference method (FDM), and feasibility of the model was verified by comparing it with the load-displacement curves obtained from laboratory tests. The results of the laboratory tests and numerical simulations showed a linear relationship between the reference strain and the DFOS strain. Therefore, a strain correction method was proposed for the DFOS based on the DEM-FDM method, and the strain correction coefficient was used as the evaluation index. In addition, an orthogonal test was performed to analyze the influence of design parameters, including elastic modulus, section height, and section width, on the accuracy of the DFOS. Through variance and range analysis, it was found that elastic modulus has a significant effect on the strain measurement accuracy, followed by the section height and the section width. In summary, this study proposed an efficient strain correction method suitable for the application of DFOS in pavements considering the material characteristics of the asphalt mixture and the embedded sensor.