超声波混凝土检测逆时偏移成像数值模拟

摘要

For studying of RTM imaging method in ultrasonic nondestructive testing of concrete imaging results,numerical concrete models were established based on the microstructure.The ultrasonic propagation in concrete was simulated by elastic acoustic wave equation.Through simulation of different parameters of the model,the imaging algorithm applied to the lower parts of a tendon duct and vertical or steeply dipping interfaces.The results showed that:RTM imaging algorithm for shape, position and size of the anomalies has a very good imaging results in pure cement mortar;in concrete aggregate different ratios of concrete has little effect on imaging algorithms;the aqueous vertical fracture in concrete detection can easily be overlooked or misjudged,but the RTM imaging algorithm can be imaged on crack.%为研究混凝土超声检测中的逆时偏移成像算法成像效果，引入了基于细观结构的数值混凝土模型，讨论了超声波在混凝土中的传播机理与成像规律。通过对不同参数模型的模拟，研究了逆时偏移成像算法对低速空洞下界面，陡倾界面的应用效果。研究结果表明：在纯水泥砂浆中逆时偏移成像算法对异常的形状、位置与尺寸都有很好的成像效果；在混凝土中其不同的骨料配比对成像算法的效果影响不大；混凝土含水垂直裂缝在检测中很容易被忽视或误判，逆时偏移成像算法能很好地对裂缝进行成像。