粘结混凝土结构超声波时域和频域特性研究

装配式建筑在后浇混凝土过程中存在不同混凝土相互结合的问题，混凝土结合面粘结质量对粘结混凝土结构的受力性能具有重要影响。为研究粘结混凝土结构在不同粘结质量情况下的声波特性，运用有限元方法建立六类粘结混凝土结构在不同粘结质量情况下的物理模型，模拟了超声波在粘结混凝土结构模型中的传播过程。通过提取时域信号峰值，对频域数据进行积分处理，对比分析了各类粘结混凝土结构在不同粘结质量情况下的时域特征和频域特征。结果表明：不同混凝土强度等级相结合的粘结混凝土结构，界面反射较强，且强度等级差别越大，界面反射越强；时域信号峰值与频域积分随着粘结界面质量的提高而增大。根据这一特征，通过试验制作了三种不同粗糙度的粘结混凝土结构样本，采用斜测法对样本进行超声测试，结果表明界面粗糙度越高，超声波透射粘结界面区域内的时域信号峰值和频域积分越大。研究结果可为粘结混凝土结构质量检测提供参考和依据。

Research on ultrasonic time-domain and frequency-domain characteristics of bonded concrete structures

In the process of post casting concrete of prefabricated buildings, there is a problem of mutual combination of different concretes. The bonding quality of concrete joint surface has an important impact on the mechanical performance of bonded concrete structure. In order to study the acoustic characteristics of bonded concrete structures with different bonding qualities, the physical models of six types of bonded concrete structures with different bonding qualities are established by using the finite element method, and the propagation process of ultrasonic wave in the bonded concrete structure model is simulated. By extracting the peak of time-domain signal and integrating the frequency-domain data, the time-domain and frequency-domain characteristics of various bonded concrete structures with different bonding qualities are compared and analyzed. The results show that the interface reflections of bonded concrete structures with different concrete strength grades are strong, and the greater the difference in strength grades, the stronger the interface reflection. The peak of time domain signal and the frequency domain integration increase with the improvement in bonding interface quality. According to this feature, three kinds of specimens of bonded concrete structure with different roughness are made through experiments, and the oblique measurement method is used to test the specimens. The results show that the higher the interface roughness, the greater the peak of time-domain signal and the frequency-domain integration in the bonded interface area of ultrasonic transmission. The research results can provide a reference and basis for the quality inspection of bonded concrete structure.