冲击弹性波法在衬砌质量检测中的应用

Application of impact elastic wave method in quality inspection of lining

输水隧洞衬砌结构存在灌注质量缺陷及脱空区时会引起渗漏或塌方等一系列危害。探地雷达是混凝土衬砌质量检测的主要方法,当衬砌表层有致密钢筋网时,其对电磁波有较强的屏蔽作用,严重影响探测效果。为了实现该工况下对混凝土衬砌进行快速、高精度检测,笔者提出一种不受钢筋网屏蔽的冲击弹性波法。该方法利用冲击脉冲震源激发弹性波,在同一直线布置2个传感器接收,通过对弹性波时间域波形特征、主频频移特征以及瑞雷波速度谱进行分析,实现综合运用多参数对衬砌缺陷位置的精确定位。该方法在某泄洪隧洞衬砌质量检测应用中成功探测出衬砌钢筋网后部脱空区的位置与规模,验证了冲击弹性波法在衬砌质量检测中的有效性和准确性。

A series of diseases such as leakage or collapse will be caused when there are perfusion quality defects and void areas in the lining structure of water conveyance tunnel.Ground penetrating radar(GPR)is an important method to detect the quality of concrete lining.When there is a dense steel mesh on the lining,it has a strong shielding effect on electromagnetic wave,which seriously affects the detection effect.In order to achieve the rapid and high-precision detection of concrete lining under this working condition,the authors propose an impact elastic wave method which is not shielded by steel mesh.In this method,the impulse source is used to excite the elastic wave and two sensors located on the same line receive elastic wave signals.Through the comprehensive analysis of the time domain waveform characteristics of the elastic wave,the shift characteristics of main frequency and the Rayleigh wave velocity changes,the lining defect position is accurately located by using these multi parameters.This method is used to detect the lining quality of a tunnel,and the position of the defect behind the steel mesh is determined successfully,which proves the validity and accuracy of the elastic wave method in the lining quality detection.