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采用边界单元法模拟与地表上一定形式分布的异常电场相对应的空气域内电磁场的变化规律,认识到:在E极化时,很难确定由Jones和Weaver等人建议的在空气域中可以忽略由地下非均质体所引起异常场的扰动影响的“合理高度”。这个高度不仅取决于地表上异常场的展布范围和异常幅度,而且还依赖于不同的观测周期。因此有必要重新考虑E极化时模型边界的选择方式。边界元与有限元耦合模型为解决这个难题提供了新的途径,它是通过研究地表上侧向延伸边界电磁场分布来避开空气域内模型上边界高度的选择这个难点的。
The boundary element method is used to simulate the variation of the electromagnetic field in the air field corresponding to a certain form of abnormal electric field distributed on the surface. It is recognized that it is very difficult to determine in the air domain that Jones and Weaver et al proposed in E polarization. The “reasonable height” of the disturbances caused by the anomalous fields caused by the underground heterogeneous bodies. This altitude depends not only on the distribution of the anomalous field on the Earth’s surface and the magnitude of anomalies, but also on the different observation periods. Therefore, it is necessary to reconsider the choice of model boundary in E-polarization. Boundary element and finite element coupling model provide a new way to solve this problem, which is to avoid the difficulty of choosing the height of the upper boundary of the model in the air domain by studying the electromagnetic field distribution extending laterally on the earth’s surface.