中文摘要：

混凝土T梁在我国桥梁建设中发挥了越来越重要的作用,由于其结构的复杂性,目前基于T梁预应力束孔管道无损检测方法正处于理论探究阶段.三维声波数值模拟作为一种有效的、常规的正演手段被大量的应用于合成记录的生成中,本文参照实际T梁模型的大小设置了一组模型参数,并进行了三维声波数值模拟,分析了不同位置所接收到的多道记录信号,给出了不同时刻剖面的波场快照图.同时,采用了S变换时频分析方法,提取了频率为25Hz时间域的能量分布图,得到了数值模拟信号的时频联合特征,在S变换时频剖面上能更加清晰的识别低速异常体的分布位置.结果表明：声波法可用于T梁预应力束孔管道无损检测中,S变换时频分析方法有助于提高声波数据解释的准确性.

英文摘要：

Concrete T-beam bridge construction has played an increasingly important role in China. Due to the complexity of its structure, the theory based on pipelines of pre-stressed concrete beams in non-destructive testing method is being explored. Three-dimensional numerical simulation of sound waves, which has been widely applied to synthetic records generation, is an effective and conventional means of forward simulation. According to the size of actual concrete beams model, a set of three-dimensional model is simulated by Finite-difference time-domain method. The multi-channel recording signal received from the different positions is analyzed, and the wave field snapshot map is displayed at different times. Furthermore, adopting to the S-transform time-frequency analysis method, we extract the time domain energy distribution from frequency of 25Hz, and obtain the signal time-frequency characteristics by numerical simulation. By processing time-frequency S-transform, we can identify the position of the low speed anomaly body clearly. The results show that the acoustic method can be used for the non-destructive testing of pipelines of pre-stressed concrete beams, and the S-transform time-frequency analysis method is valuable to improve the accuracy of the acoustic data interpretation.