基于合成孔径聚焦技术的煤岩超声成像检测研究

Coal-rock ultrasonic imaging and testing research based on synthetic aperture focusing technology

为了提高超声波换能器检测煤岩界面的成像效果,分析煤岩声阻抗差异和超声波指向性的特征,提出了超声波合成孔径聚焦的煤岩成像检测.基于非均质散射场理论,建立煤岩声场模型,开展了煤岩模型的超声波合成孔径聚焦成像检测的数值模拟,获得了不同类型煤质模型的成像图像.采用超声波合成孔径聚焦成像检测方法,完成了0.4和0.5m煤厚的模拟样成像检测实验与理论研究.仿真与实验结果表明,基于非均质散射场理论的煤岩合成孔径聚焦超声波成像检测建模与数值模拟是正确的,合成孔径聚焦技术有效地提高了超声波成像检测图像的分辨率.

Analyzing the acoustic impedance difference between coal and rock and the ultrasonic directivity,a coal-rock imaging and testing method using ultrasonic synthetic aperture focusing technology was proposed to improve the image resolution for detecting coal-rock interface.The sound field model of coal-rock was built based on the theory of heterogeneous scattering field.Using the synthetic aperture focusing technology,the numerical simulations of the model＇s ultrasonic imaging and testing were carried out.Then imaging pictures of the model with different acoustic speed in coals were obtained.The experimental and theoretical imaging and testing on the simulated samples of two different thickness（0.4 and 0.5 m）were carried out by ultrasonic synthetic aperture focusing method.The results show that the method of coal-rock model based on the theory of heterogeneous scattering field and its numerical simulation based on synthetic aperture focusing technology are correct.The synthetic aperture focusing technology can obviously improve the resolution of ultrasonic imaging picture.