电感性耦合对地电阻率交流观测的影响

Effect of inductive coupling on the alternating current observation of geoelectrical resistivity

摘要:

地电阻率交流观测方法中存在电感性耦合效应,会影响观测值的准确性。理论研究表明电感性耦合效应与供电信号频率、供电线与测量线间距离以及线路间平行走线的长度等条件相关。为了探讨理论研究与实际观测的一致性,在江苏省高邮地电台进行电感性耦合效应对地电阻率交流观测影响研究的实验,实验通过改变观测电极间的布线,分析上述条件对地电阻率交流观测结果的影响。实验结果表明,减小平行长度、增大线间距离、减小供电信号频率均能够减小电感性耦合效应,此结果与理论分析一致。当供电信号频率低于0.5 Hz时,平行长度与线间距离的变化对电感性耦合效应的影响较小,可忽略不计;当供电信号频率大于1 Hz时,为降低电感性耦合效应的影响,需要随供电信号频率增加,减小线间平行长度或增大线间距离。

Abstract:

In the alternating current (AC) observation of the geoelectrical resistivity, the observation accuracy is affected by the inductive coupling effect. Theoretical studies have shown that the inductive coupling effect is related to the electrical frequency, the distance between the current circuit and the potential circuit, and the parallel length of the two circuits. To verify the consistency between the theoretical and experimental observation results, we rearranged the wiring paths of the electrodes and conducted an AC geoelectrical resistivity observation experiment at the Gaoyou seismic station in Jiangsu Province. The results show that when the parallel lengths of the circuits and the electrical frequency decrease, the inductive coupling effect is reduced. Also, when the distance between the circuits increases, the inductive coupling effect is reduced. These results support our theoretical analysis. In addition, the effects of parallel length and distance between circuits on the inductive coupling effect can be ignored when the electrical frequency is below 0.5 Hz. When the electrical frequency increases to 1 Hz, it is necessary to avoid the inductive coupling effect by decreasing the parallel length or increasing the distance between circuits.