带缺陷隧道底板结构空气耦合冲击回波响应特性研究

Air Coupled Impact Echo Response in Tunnel Floor with Different Defects

针对隧道底板中空腔、含水、裂缝等结构内部损伤情况,为提高传统接触式冲击回波方法的检测效率,从气-固耦合的角度出发,以空气作为底板结构与检测系统之间应力波传播的耦合介质,开展隧道底板结构内部缺陷的空气耦合冲击回波响应特性研究。研究结果表明:1)采用空气耦合冲击回波的方法确定的底板结构内部缺陷深度与缺陷理论深度值基本吻合;2)检测系统的精度与缺陷尺寸及深度有关,随着缺陷尺寸的减小及深度增加,检测精度逐渐降低;3)空气耦合冲击回波方法对空腔和含水缺陷的检测效果优于裂缝缺陷检测效果。

For the internal damage of hollow cavity,water content,cracks and other structures of tunnel bottom plate.To improve the detection efficiency of traditional contact type impact echo method,the air coupling impact echo response characteristics of internal defects in tunnel floor structure is conduced from the perspective of gas-solid coupling,and regarding the air as the stress wave transmission coupling medium between floor structure and detection system.The results indicate follows.(1)The defeat depth in floor structure determined by air coupled impact echo method is basically consistent with the theoretical one.(2)The detection accuracy is related to the size and depth of defects,and the detection accuracy gradually decreases as the size and depth of defects increase.(3)The detection effect of this method for defects of hollows and water contain is better than that for defect of cracks.