【摘要】 针对市政工程非金属给排水管道堵塞点定位工程问题,文章从探地雷达(ground penetrating radar,GPR)信号受迫响应频域角度识别管道内水位以实现对堵塞点定位。对于非金属管道,以PVC管为代表建立时域有限差分(finite-difference time-domain,FDTD)正演模型,演示了电磁波在PVC管道内的受迫响应过程;分别使用矩阵束法和快速傅里叶变换(fast Fourier transform,FFT)法取得受迫响应频率,进一步由正演计算得出不同水位高度受迫响应频率曲线;由受迫响应频域识别的影响因素分析,得出识别误差受入射波带宽和填埋土层介电常数影响较大;设计了沙槽实验模型,获取不同水位的GPR实测数据;对实测数据进行分析,并应用FDTD正演模型进行拟合,拟合结果与实际相符合。更多还原

【Abstract】 The novel solution to locate the nonmetallic pipeline jam in the municipal engineering is proposed.It is based on the ground penetrating radar(GPR)detection,using the target’s forced response frequency domain to identify the water level in the pipeline.According to the identification,the point of piping blockage is positioned.Taking the PVC pipe as an example,the finite-difference time-domain(FDTD)forward model is built,so that the electromagnetic wave’s forced response process in the pipeline is demonstrated.Matrix pencil method and fast Fourier transform(FFT)are used to calculate the forced response frequency respectively.Furthermore,the trend curve that shows the different forced response frequency of different water level in pipeline is drawn.Influence factors of forced response frequency are also discussed.It is shown that the GPR’s bandwidth and the soil’s dielectric constant around the pipe have effect on the forced response frequency.Finally,a sand tank experimental model is designed to get GPR measured data of different water level.The FDTD forward model is used to fit the measured data,and it is concluded that the identification is consistent with the theory.更多还原