Research On Response Characteristics Of Three-component Magnetic Field Of Ground-airborne Electromagnetic Method In Frequency Domain

The ground-space electromagnetic method combines the characteristics of the ground electromagnetic method and the aviation electromagnetic method,has high field construction efficiency and detection accuracy,and is suitable for rapid and highprecision detection in areas with complex terrain conditions.At present,the theoretical research and application of ground-airborne electromagnetic method at home and abroad focus on detection method in the time domain.The collected data are mostly response signal of vertical magnetic field component(Hz).In order to further improve the detection accuracy and enrich the ground-space electromagnetic detection technology system,the paper uses theoretical analysis and numerical simulation methods to study the response characteristics and influencing factors of the magnetic component in the three directions of x,y and z.Firstly,the three-component response formula of the magnetic field in the groundairborne system is theoretically studied.The numerical simulation calculation method of the three-dimensional geological model is realized by using COMSOL software.The study found that the numerical simulation results are basically consistent with the magnetic field response curve of the analytical solution,the relative error of each component is less than 5%.The comparison results verify the correctness of the simulation method in this paper.Secondly,the variation law of the three components of the magnetic field with the electric dipole moment,offset,flying height and other factors in the ground wire electromagnetic detection system of long wire source is analyzed.The results show that the curve shape of the three components of the magnetic field is basically unchanged,and the response intensity changes As the electric dipole moment increases,the response of the three-component magnetic field becomes larger;as the offset increases,the response intensity of each component of the magnetic field gradually decreases after the offset is greater than 400m;as the flight height increases The shape of the response curve of the three components of the magnetic field is basically unchanged,and the amplitude gradually decreases.Then,the responses of the two-layer and three-layer models and the uniform half-space model are compared,and it is found that the response of the three components of the magnetic field has different responses but the shapes are basically similar,and the curve change trend has certain rules.Finally,the study of the electromagnetic field three-component response characteristics of geological anomalies such as mined-out areas and collapse columns shows that the real and imaginary parts and amplitude response curves of the threecomponent magnetic field of the anomaly body model are basically symmetrically distributed about the anomaly location,and there are peaks and valleys on the curve The appearance of the value,peak value and valley value reflects the position of the abnormal body,and at the same time it can distinguish the tendency of the abnormal body.The results of this study enrich the technology system of the three-component detection method of the ground-space electromagnetic method in one step,which provides a theoretical basis for further research and development.