地电阻率观测装置布设与金属管线类干扰的关系研究--以平凉台为例

Relationship between the layout of geo-electrical resistivity observation device and the interference of metal pipelines:a case study of Pingliang station

以平凉井下地电观测装置为例,采用有限元数值模拟的方法分析地电阻率观测装置布设与金属管线类干扰的关系。结果表明:(1)垂直于测线方向的金属管线对地电阻率观测的影响明显小于平行于测线方向的影响,最有效的抑制方法是增大金属管线的避让距离。(2)金属管线位于布极中心区域时,加深电极埋深并不一定能有效抑制干扰;对于金属管线垂直于测线方向的情况效果是显著的,但对于平行于测线方向的情况效果并不理想。(3)金属管线对井下地电阻率观测的影响是相对复杂的,它与装置系统(观测极距、电极埋深)、分层介质电性结构、金属管线自身的属性(电导率、横截面积、长度、距离)等因素有关。本研究方法可以快速判定资料异常变化的性质,对异常跟踪工作具有一定的参考意义,还可以为新建井下地电观测装置提供理论依据,从而提高台站的观测效能。

Taking the underground geo-electrical resistivity observation device at Pingliang station as an example,this paper analyzed the relationship between the layout of geo-electrical resistivity observation device and the interference of metal pipelines by using the finite element numerical simulation method.The results show that:(1)The influence of metal pipeline perpendicular to the survey line on geo-electrical resistivity observation is significantly less than that parallel to the survey line.The most effective suppression method is to increase the avoidance distance of metal pipeline.(2)When the metal pipeline is set in the center of electrodes,the increase of the buried depth of electrode may not effectively suppress the interference.The effect is significant when the metal pipeline is perpendicular to the survey line direction,but it is not ideal when it is parallel to the survey line direction.(3)The influence of metal pipeline on the underground geo-electrical resistivity observation is relatively complex,which is related to many factors,i.e.,the device system(observation polar distance,electrode buried depth),the layered medium electrical structure,and the properties of metal pipeline(conductivity,cross-sectional area,length,distance),etc.The method proposed in this paper can quickly determine the abnormal changes of data,thus having a certain reference significance for anomaly tracking.It can also provide a theoretical basis for the new underground geo-electrical resistivity observation device,so as to improve the observation efficiency of station.