直流输电线路对地电阻率的观测干扰

Interference on Geoelectrical Resistivity Observation from DC Power Transmission Line

直流输电线路对地震台地电阻率观测的干扰影响是目前亟需解决的问题。根据地电阻率观测仪器的工作原理,分析了直流输电线路干扰地电阻率观测的原因。针对直流线路接地极不同形状,考虑大地为水平分两层的土壤模型,基于等值复数镜像法推导出单一垂直接地体、水平双环接地体、多个垂直接地体入地电流在土壤中的电位计算公式,计算并分析了多种情况下直流线路对地电阻率观测的干扰水平。计算结果表明,采用水平双环形接地极可减小50%左右的干扰值,采用4个垂直接地极可减小75%左右的干扰值。

The interference on the geoelectrical resistivity observation from DC power lines is a key issue puzzling seismic monitoring.According to the working principle of geoelectrical resistivity observation instrument,the interference reason on geoelectrical resistivity observation was analyzed.The calculation formulas of potential in soil,which is represented as horizontal twolayer electrical model,are derived by equivalent complex image method responding to the ground electrodes of DC power line with different shapes：one vertical ground electrode,horizontal double-ring ground electrode and four vertical ground electrodes.Therefore,the interference values on geoelectrical resistivity observation from DC power lines under various situations were calculated and researched.The calculation results show that interference value could be reduced 50%for horizontal double-ring ground electrode,and could be reduced by 75%for four vertical ground electrodes.