摘要
地下管线实际形状与准确位置的确定是探地雷达图谱解释的主要内容之一.制约管线探地雷达反射归位精度最主要的因素是电磁波在地层中的传播速度,如何准确确定电磁波传播速度是探地雷达偏移处理能否成功的关键.为便于对探地雷达图谱特征进行定量解释,开展了不同大小、埋深与重叠等情况管线的正演模拟与模型实验.结合小波熵理论与频率波数偏移成像方法,提出了一种基于小波熵的探地雷达频率波数偏移成像方法,将其应用于地下管线正演模拟与模型实验探地雷达信号偏移处理.研究结果表明:探地雷达图像经基于小波熵的频率波数偏移处理后,电磁波速度的估计值与真实值误差可控制在2%以内;随着管线管径大小与埋置深度的增加,绕射双曲线的开口弧度不断增大,管与管之间绕射波交叉干扰越严重;探地雷达信号经基于小波熵的频率波数偏移处理后可大大提高图像的分辨率,压制了多次波的干扰,使绕射双曲线更收敛,能量更聚焦,从而有利于地下管线实际形状与具体位置的准确提取.研究结果对城市地下管线探地雷达图谱解译工作提供技术支持.
Determination of actual shape and accurate position of underground pipeline is one of the main contents of map interpretation of Ground Penetrating Radar(GPR).The most important factor to restrict accuracy of GPR reflection homing is the propagation speed of electromagnetic waves in the formation.Thus,how to accurately determine propagation speed of electromagnetic waves is the key issue to get succeed in GPR migration processing.In order to improve the quantitative interpretation of the characteristics of the ground penetrating radar map,the forward simulation and model experiments of pipelines with different sizes,buried depths,and overlaps were carried out.Combining wavelet entropy theory with frequency wavenumber migration method,a frequency wavenumber migration imaging method of GPR based on wavelet entropy was proposed.This method was applied to the migration processing of underground pipeline in the GPR forward simulation and model experiments.The results show that the error between the estimated value of electromagnetic wave velocity and the true value can be controlled within 2%after the GPR image processed.With the increase of pipeline diameter and buried depth,the opening arc of the diffraction hyperbola become larger,and the cross-interference of the diffraction wave between the pipelines become more serious.The resolution of GPR signal can be greatly improved after frequency wavenumber migration processing,the interference of multiple waves can be also suppressed,the diffraction hyperbola is more converged,and the energy is more focused,which is beneficial to the accurate extraction of the actual shape and position of underground pipeline.Therefore,the results provide technical support for the interpretation of urban underground pipeline GPR maps.
作者
张胜
邹雨驰
何文超
洪亮
李留玺
ZHANG Sheng;ZOU YuChi;HE WenChao;HONG Liang;LI LiuXi(School of Civil Engineering,Hunan City University,Yiyang 413000,China;Hunan Engineering Research Center of Structural Safety and Disaster Prevention for Urban Underground Infrastructure,Yiyang 413000,China;Department of Mechanical Engineering,University of Houston,Houston 77204,USA;School of Civil Engineering,Changsha University of Science and Technology,Changsha 410114,China)
出处
《地球物理学进展》
CSCD
北大核心
2021年第2期840-847,共8页
Progress in Geophysics
基金
国家自然科学基金项目(51608183和51678226)
国家留学基金项目(201808430341)
湖南省自然科学基金项目(2018JJ3022,2019JJ50030)
湖南省大学生创新创业训练计划项目(S201911527018)
湖南城市学院土木工程国家级实验教学示范中心大学生创新实验计划项目联合资助.
关键词
地下管线
探地雷达
小波熵
频率波数偏移
正演模拟
模型实验
Underground pipeline
Ground Penetrating Radar(GPR)
Wavelet entropy
Frequency wavenumber migration
Forward simulation
Model experiment
