砂浆与轨道板离隙或脱空是高铁无砟轨道结构中最常见和最严重的损伤形式，关系到高速列车的正常运营和乘客的人身安全。鉴于二者粘接而成的复合结构属于典型的层状薄板结构，本项目将挖掘超声导波在粘接界面无损评价方面的潜力，研究存在局部粘接界面缺陷的无砟轨道结构兰姆波检测方法。从理论上建立包含局部弱粘接界面的多层介质兰姆波传播模型，寻求对界面性质敏感的兰姆波模式；考察兰姆波传播特性与界面缺陷特征之间的关系，探究兰姆波与界面缺陷相互作用机理；发展有效的信号处理方法，提取真正的缺陷信号并从混叠的多模式信号中分离出所需要的模式；探索基于全波场信息的异常（缺陷）波成像算法，提高定量化缺陷图像的分辨率和精度。从实验上研究空气耦合超声兰姆波信号的激发、传播和最佳接收。本项目研究成果在学术上提供解决含局部弱粘接界面缺陷兰姆波传播问题的新途径，在应用上为高铁无砟轨道结构粘接界面缺陷的兰姆波无损评价奠定理论基础。

Interfacial gap or debonding between the mortar and track slab is the most common and serious injury form in the ballastless track structure of high-speed railway, which is related to the normal operation of high-speed trains and the safety of passengers. In view of their bonding structure belonging to a typical laminated sheet structure, this project will dig the potential of ultrasonic guided waves in nondestructive evaluation of bonding interface and explore the Lamb wave detection method for ballastless track structure with localized bonding interface. The model of Lamb wave propagating in multilayer structure with localized weak adhesion interface is theoretically established so as to select the inspecting Lamb mode that is sensitive to interfacial property. The relationship between Lamb wave propagating characteristics and the interfacial defect features is established for exploring the mechanism of interaction of Lamb wave with the interfacial defect. Effective signal processing method is developed to extract the real defect signal and separate the desired mode from the aliasing multiple modes. This project will research anomalous defective wave imaging algorithm based on the full wave field data, so as to improve the resolution and precision of quantitative defect map. The excitation, propagation and best reception of air-coupled ultrasonic Lamb wave signals are experimentally studied. The achievements of this project will provide a new academic way for Lamb wave propagation problem with localized weak adhesion defect and lay the theoretical groundwork in the application for Lamb wave nondestructive evaluation of the interfacial defects in the high speed railway ballastless track structure.