井地电法点电源供电地表异常电场分布特征实验研究

Experimental study on abnormal electric field distribution of surface-borehole electrical method

井地电法供电点位置与地表电位分布关系密切。为研究点电源供电时供电点位于电性异常层上、下不同位置时地表电位的分布特征,通过物理模型研究的方法,采用铜圆柱体作为固定的点电源供电,利用有机玻璃模拟高阻体,通过三维电位观测系统,获得高阻体位于供电源上、下不同深度时水面测得的电位值,计算该值与无异常体存在所测得的背景场电位值的差值作为异常电场,进一步分析异常电场的特征,推断异常体的空间展布情况。模拟实验表明,点源供电时供电点与异常体越近,其地表异常电位值越高,并且供电点源位于异常体下方时其在地表的异常形态越接近其真实形态。

The surface potential distribution is related to the position of electrical power supply. In order to study the potential distribution with the change of power supply position, we did a series of flume simulation experi- ments, using a copper cylinder as a power supply point source, plexiglass plate as an oil layer, utilizing three-di- mension resistivity method to test the surface potential of every point arranged on the surface of the water. The dis- tribution potential on surface may provide physical basis for analyzing distribution of oil layer. The result of simula- tion experiment shows that as the abnormal body is closer to the power supply point, the measured anomaly voltage on the surface is higher. When the supply point located below the anomalous body, the distribution of anomaly volt- age is closer to the shape of the anomalous body. The character of the electric field can be effective to display the disturbance of high resistance body buried below.