超声阵列方法在层状结构损伤检测中的应用*

层状钢筋混凝土结构常见的裂缝、层间离缝等损伤具有尺度小、隐蔽的特点，常规检测方法无法对其精确查明与定量评价。以高铁层状无砟轨道结构为研究对象，使用阵列式超声装备采集半矩阵数据，利用全聚焦算法对轨道内部结构及损伤成像，通过线性旅行时插值射线追踪算法计算超声波在层状介质中传播的最短到达时间代入全聚焦成像公式，具有深度准确、分辨率高、聚焦性好的特点。提出一种层间密实度评价方法，以表面超声直达波能量为基准分析反射波能量差异计算密实指数，可定量分析无砟轨道层间状态。文中层状介质的检测和层间损伤定量评价方法有效查明层状无砟轨道层内裂缝和层间离缝，对使用超声波检测层状结构及层间损伤具有借鉴意义。

Application of ultrasonic array method in damage detection of layered structures

The damage of layered reinforced concrete structure, such as cracks and disjoint between layers, is small and hidden. It can not be accurately identified and quantitatively evaluated by conventional detection methods. The layered ballastless track structure of high-speed rail is taken as the research object. The half-matrix data are collected by the array ultrasonic equipment, and the internal structure and damage of the track are imaged by the total focusing method (TFM). The shortest arrival time of ultrasonic wave propagation in layered media is calculated by linear travel time interpolation (LTI) ray tracing algorithm. As a result, TFM has higher resolution, more accurate depth, and better focus. An evaluation method of interlayer compactness is proposed. The density index is calculated by analyzing the difference of reflected wave energy based on surface ultrasonic direct wave energy, which can quantitatively analyze the interlayer state of ballastless track. In this paper, the method can effectively identify the intra-layer cracks and interlayer separation cracks of lamellar ballastless track, which has a reference significance for the use of ultrasonic detection of lamellar structure and interlayer damage.