Study On The Time-domain Numerical Simulation Of Mine Advanced Detection With Transient Electromagnetic Method

As the fundamental research content, the numerical simulation of mine advanced detection technology plays an extremely important guide role in mine electromagnetic detection and data interpretation. The numerical simulation technology will rise the positive effect to improves the mine advanced detection technology with transient electromagnetic method.On the basis of the summery and analysis of the present numerical computing methods, we choice the Finite-difference Time-domain (FDTD) method as the simulation method. FDTD has the special Yee grid structure; it can be operated easily and easy to handle the electromagnetic scattering or radiation problems which maybe contain complicated shape and multimedia object. With more freedom in resolving medium, FDTD is method is explicit, which can present abundant time-domain information of the physical process and show legible physical picture of complicated physical process.This paper gives the special form of Maxwell equations in conductive medium under quasi-static condition, and the boundary condition in the interface of different media. In-depth study of Helmholtz theorem in the geophysical infinite space,the radiation condition,uniqueness theorem, and gives a detailed proof.On this basis, the paper discuss the time-domain Maxwell curl equations, under quasi-static conditions, establish the discrete form FDTD equation and add a constraint on. Using the infinite space radiation conditions replace absorbing boundary conditions to reduce the computational region. Paper derives the PML absorbing boundary conditions equation in TE model, and accomplishes the FDTD simulation program.Under the incentive of Gauss pulse, the TEM simulation results that, when the distance from the low resistance anomalous body to heading face is 10m,50m,100m, the longer as the anomalous body stay away the heading face, the later the wave reflected; The send out pulse signal transmit directly with the time, and spread around, it would be reflected when the signal encounter quarters. The simulation results consistent with the electromagnetic wave propagation, and interaction rules and the law of interaction between objects. The result proves that the FDTD equation and the simulation program is correct in this paper. The distribution of electromagnetic parameters vary with time in heading face, the spreading and dissemination of pulse signal, reflection of abnormal body, reflection of side leading, the reflection time that different distance from the heading face to abnormal body, all these provide reference to improve the TEM advanced detection technology and the development of instrument.