Finite Element Two-dimensional Forward Modeling Of Point Source DC Method

Direct Current Electric Methods is an important branch of electrical exploration.It has been widely used in the study of hydrology,coal fields,engineering geology,and crustal structure.The forward problem of direct current method is known geoelectric model and field source distribution,solving the distribution law of electric field,which is the basis of inverse problem of direct current method.In this paper,the finite element method is used to simulate the point power field based on the Helmholtz equation.The wave number k is obtained by using the integral equation method,and the coefficient g is obtained by solving the overdefinite equation.On this basis,the inverse Fourier transform is realized,and the two-dimensional finite element numerical simulation of point source direct current method is realized.In order to verify the accuracy of the numerical solution,the paper through the method of separation of variables dc level of one-dimensional layered model was deduced the surface potential analytical solution,using numerical integral calculating a dragon begg d horizontal layered model(second layers,three layers and four layers),analytic solution of the one-dimensional layered terrain analytic solution and homogeneous half space analytical solution and numerical solution,the accuracy of the numerical solution is proved.The paper establishes different geoelectric models,and obtains the potential distribution law of different electrical geological anomalous body fields under the condition of point source power supply through finite element forward modeling,and obtains the potential difference of the measuring electrodes at different positions,and calculates the simulated measurement.In the case of apparent resistivity,the corresponding apparent resistivity profile is plotted;and compared with the results obtained from the tank simulation,the lateral and vertical resolutions of the single-sided and bilateral power supply and different measuring devices are analyzed.The research results of the thesis provide a theoretical basis for actual production.