ABSTRACT

Damage in a pavement structure is usually initiated in the asphalt layers, making the Rayleigh wave ideally suited to the detection of shallow surface defects. However, the practical application of crack detection methods in asphalt is hampered by the dispersive behaviour of the road pavement. A new digital signal processing technique for the measurement of the amplitude and phase of the direct and reflected Rayleigh waves, scattered from the boundaries of a vertical crack in asphalt, is presented in this paper for the first time. The method uses multiple receivers and hence it finds an approximate solution with a least square optimisation. The resonant peak frequencies of the reflection coefficient and the cut-off frequencies of the transmission coefficient are used for assessing the depth of the crack. The method proved to be successful for the in-situ assessment of the depth of cracks both numerically and experimentally, since it can cope with the dispersive and heterogeneous nature of asphalt. This work supports a paradigm-shifting approach to the in-situ crack evaluation of roads, for which the road is holistically treated as a dispersive medium.

摘要

路面结构的损坏通常始于沥青层，这使得瑞利波非常适合检测浅表层缺陷。然而，裂缝检测方法在沥青中的实际应用受到路面分散行为的阻碍。本文首次提出了一种新的数字信号处理技术，用于测量从沥青垂直裂缝边界散射的直接和反射瑞利波的幅度和相位。该方法使用多个接收器，因此它找到了具有最小二乘优化的近似解。反射系数的谐振峰值频率和透射系数的截止频率用于评估裂纹的深度。该方法被证明是成功的通过数值和实验对裂缝深度进行原位评估，因为它可以处理沥青的分散性和非均质性。这项工作支持对道路原位裂缝评估的范式转换方法，为此，道路被整体视为分散介质。