摘要
人工源近区频率域电磁法具有轻便、分辨率高及抗干扰能力强等优点,但提取地质体二次场响应难题困扰了该方法推广应用。基于等值反磁通原理提取二次场响应,首先,推导出了基于等值反磁通原理的频率域近场垂直磁场响应的表达式;然后,采用层状介质与均匀半空间介质的垂向磁场同相分量的比值定义视电阻率,并计算了典型层状介质垂直磁场的频率响应;最后,通过试验对比时间域与频率域方法对浅埋藏铝板的异常响应。研究结果表明:基于等值反磁通原理能够有效提取近场频率域二次场信号,近场垂向磁场的同相分量与大地电导率的二次方成正比;垂向磁场同相分量的比值定义视电阻率能够清晰反映A型、Q型、H型及K型地电断面的特征。
The frequency domain electromagnetic sounding method in the near-field of artificial sources has advantages such as portability,high resolution,and strong anti-interference ability.However,the problem of extracting the secondary field response of geological bodies has hindered the widespread application of this method.By extracting the secondary field response based on the principle of equivalent opposing coils,this study first derives the expression of the frequency domain near-field perpendicular magnetic field response based on the principle of equivalent opposing coils;then,the ratio of the in-phase component of the vertical magnetic field of layered media to that of homogeneous half-space media is defined as the apparent resistivity and the frequency response of the vertical magnetic field for typical layered media is calculated;finally,a comparative experiment is conducted to compare the anomalous responses of the time domain and frequency domain methods to shallow-buried aluminum plates.The results show that the princi ple of equivalent opposing coils can effectively extract the near-field frequency domain secondary field signals based on the principle of equivalent opposing coils,and the in-phase component of the near-field vertical magnetic field is directly proportional to the square of the magnetotelluric conductivity.The apparent resistivity defined by the ratio of the in-phase component of the vertical magnetic field can clearly reflect the characteristics of A-type,Q-type,H-type,and K-type geoelectric cross section.
作者
席振铢
杨晓敏
郭涛
龙霞
赖耀发
吴倩
Xi Zhenzhu;Yang Xiaomin;Guo Tao;Long Xia;Lai Yaofa;Wu Qian(School of Geosciences and Info-physics,Central South University;Hunan 5D Geophyson Co.,Ltd.;Guangzhou Urban Planning&Design Survey Research Institute)
出处
《黄金》
CAS
2024年第1期61-68,共8页
Gold
基金
国家重点研发计划项目(2022YFC2903404)。
关键词
频率域电磁测深
等值反磁通
同相分量
近区测量
视电阻率
异常响应
frequency domain electromagnetic sounding
equivalent opposing coils
in-phase component
near-field survey
apparent resistivity
anomalous response
