Detection and Characterization of Cracks in Highway Pavement with the Amplitude Variation of GPR Diffracted Waves: Insights from Forward Modeling and Field Data

Shili Guo,Zhiwei Xu,Peimin Zhu,Xiuzhong Li

doi:10.3390/rs14040976

Shili Guo, Zhiwei Xu + Show 2 more

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https://doi.org/10.3390/rs14040976

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Abstract

It is important to distinguish between two common defects, fatigue cracks and reflective cracks, and determine their locations (the top and bottom) in the highway pavement because they require individually targeted treatment measures. Ground Penetrating Radar (GPR) has the potential to detect cracks in the highway pavement due to the change of the electromagnetic properties of highway-pavement media, arising from the existences of cracks. By using a theoretical analysis and a numerical simulation, we compare the characteristics of corresponding radargrams, including the amplitude variation of diffracted waves with various models of presetting cracks inside the layered homogeneous media. For those fatigue cracks and reflective cracks extending to the road surface, the amplitude curves of direct ground wave can intuitively indicate the locations of the top of the cracks and qualitatively compare the width of these cracks. Furthermore, we find that the shape and pattern of diffraction hyperbolas of both types of cracks with bottoms at different locations are quite similar, but their amplitudes are significantly different. To be specific, for those cracks with the same width, the amplitude of diffracted waves generated by fatigue cracks is slightly higher than that generated by reflective cracks at the interface between the asphalt surface and the semi-rigid base layer. In contrast, the amplitude of the former is significantly lower than the latter at the interface between the semi-rigid base and the roadbed. We applied these findings to the interpretation of the field GPR data of a highway pavement in China, and successfully identified the locations of the cracks and corresponding types. Our model results and field results clearly show the efficiency of our findings in the detection of cracks for highway-pavement rehabilitation.

Highlights

By the end of 2020, the total mileage of highways in China reached over 161,000 km, ranking it as first in the world
The highfrequency electromagnetic wave emitted by Ground Penetrating Radar (GPR) will generate a diffracted wave when it encounters an isolated “point” during propagation, and its travel time curve is a classical hyperbola
Based on the finite difference time domain (FDTD) method and the convolutional perfectly matched layer (CPML) absorption boundary condition [30], the numerical simulation of GPR data was carried out using a Blackman-Harris pulse with a center frequency of 900 MHz

Summary

Introduction

By the end of 2020, the total mileage of highways in China reached over 161,000 km, ranking it as first in the world. Based on the design concept of “Strong base, Thin surface”, the vast majority of highways in China adopt the layered structure, i.e., a semi-rigid base layer overlaid by an asphalt pavement [1,2]. The pavement structure is an essential part of the highways that directly contributes to improving safety and vehicle comfort and reduces fuel consumption. The pavement structure usually suffers from a number of defects (e.g., cracks, voids, and delamination). Among the various pavement defects, fatigue cracks and reflective cracks are considered as two major failure modes of the pavement structure [3]. Fatigue cracks are mainly imposed by repetitive traffic loading [4]. They usually crack from top to bottom, and only occur in the asphalt

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