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用基于张量格林函数的体积分方程对三维异常体进行瞬变电磁响应的正演模拟 ,首先在频率域内计算电磁场分量的频率域响应 ;然后利用快速数字滤波技术将计算结果转换到时间域。文中分别通过对五层地电模型表面的水平电偶极子和接收器下方不同深度的水平导电薄板的瞬变电磁场响应进行计算 ,并作了详细分析。结果表明 :当导电异常体位于场源下方时 ,其近源影响非常大 ;同时表明随着异常体与周围介质电导率对比度的增大 ,当异常体埋深增大时 ,瞬变电磁 (TEM)法对其探测能力反而有可能会增大。
The forward modeling of transient electromagnetic response of three-dimensional anomalous body is carried out by means of volume integral equation based on tensor Green’s function. Firstly, the frequency domain response of electromagnetic field component is calculated in the frequency domain. Then the calculation result is transformed into the time domain by fast digital filtering. In this paper, the horizontal electromagnetic dipole on the surface of the five-layer geoelectric model and the electromagnetic field response of the horizontal conductive thin plate under the receiver are calculated and analyzed in detail. The results show that the near-source influence is very large when the conductive anomaly is located below the field source. At the same time, it shows that as the contrast of the anomalous body and the surrounding medium increases, ) Act on its detection capabilities but may increase.