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首先给出瞬变电磁(TEM)场卷积计算式,并将关断电流变化率函数看成冲击函数,垂直阶跃脉冲激发的场分量看成输入信号,卷积结果就是任意形状关断电流的TEM响应。把电流激发脉冲看成是许多垂直阶跃函数的叠加,通过叠加这些阶跃函数的响应求得任意电流脉冲激发的瞬变电磁响应。当已知TEM场的实测值和关断电流形状,就可按编程的方法计算全期视电阻率。文中给出了2个斜坡关断电流激发的电偶极源TEM垂直磁场算例,一个为均匀半空间的响应及其全期视电阻率,另一个为三层K型地电断面的响应及其全期视电阻率。
Firstly, the convolution formula of transient electromagnetic field (TEM) is given, and the function of the rate of change of shutdown current is taken as the impulse function. The field component of the vertical step pulse excitation is regarded as the input signal. The convolution result is any shape shutdown current The TEM response. The current excitation pulse is considered as a stack of many vertical step functions and the transient electromagnetic response of any current pulse excitation is found by superimposing the response of these step functions. When the measured values of the TEM field and the shape of the shutdown current are known, the full-term apparent resistivity can be calculated programmatically. In this paper, two examples of TEM vertical magnetic field induced by the turn-off current of dipole are presented. One is the response of a uniform half-space and its entire apparent resistivity and the other is the response of a three-layer K-type geoelectric section Its full-term apparent resistivity.