Two-dimensional Finite Element Method Forward Simulation For GPR In The Dispersive Medium

The ground-penetrating radar (GPR) is an important shallow geophysical exploration method, to carry out the forward simulation is an important topic about GPR. But most of the ground penetrating radar forward studies did not consider the attenuation of the medium, thus there is a certain deviation of the measured radar wave form. Taking it into account that the actual subsurface media are dispersive medium, radar electromagnetic wave often produces attenuation and distortion in its propagation process, which is bound to affect the interpretation effect of data, so, this paper combines the finite element method to do the forward simulation for GPR in the dispersive medium with a great advantages that it doesn’t need to calculate the internal boundary conditions, apply to the physical properties of complex issues, and the solution process is standardized and so on. Obviously it is closer to the detection reality and instructive to the actual work.The paper is funded by a joint support of the National Natural Science Fund "The complex GPR element-free method forward simulation and multi-parameter hybrid intelligent optimization inversion"(41074085)and "The research of GPR’s forward modeling and migration based on finite element of wavelet"(40804027)Firstly, this thesis reviewed the history of the development and the current status of ground-penetrating radar equipment, applications and the GPR forward simulation. Elaborated the basic principles of GPR and operating parameters of the principle of selecting. Deeply analyzed of the causes and effects of dispersion generated and illustrated the relationship between the monochrome frequency attenuation, frequency dispersion, frequency, dielectric constant and resistivity in a comparison diagram form.Then started from the Maxwell equation which met the GPR, and presented the finite element GPR wave equation which satisfied the Debye relationship, then deduced the equation finite element discretization format, loaded the transmission absorbing boundary conditions, and the stable and efficient solution of mass matrix. A GPR forward simulation program considered attenuation is prepared based on MATLAB software platform. By using this program a number of typical geoelectric model was simulated and forward simulation profile and snapshot of wave field were obtained. The result of the GPR forward simulation considered dispersion is compared with the Non-dispersive medium conditions simulation. The results show that radar wavelet width changes in dispersive medium, and becomes larger as the distance increases, radar wave attenuates faster in the dispersive medium than in the non-dispersive medium. The conclusion is full of guiding signification for study of the influence of medium on electromagnetic wave attenuation and dispersion. At the same time it verified the feasibility and effectiveness of the proposed algorithm.49pictures,3sheets,65references.