地铁对井下地电阻率观测的影响分析——以江宁台为例

Influence of the Subway on Deep-well Resistivity Observation:A Case Study of Jiangning Station

南京江宁台距地铁S1、S7、S9号线最近距离均小于3.2 km,地铁对地电阻率观测造成很大影响。本文结合部分地铁测试方案,分析了该台2016—2018年井下地电阻率观测数据,初步探讨其正负脉冲型突跳、上升、下降变化的机理,并比较地表和井下地电观测的数据最大变化幅度。结果表明:井下短极距观测能够减轻地铁干扰,当地铁线路增加时,干扰也相应增加,地铁试运行对地电观测的干扰通常强于正式运营。

Jiangning station in the city of Nanjing is less than 3.2 km from the S1,S7,and S9 Metro Lines and the subway can have a significant effect on deep-well observations.In this paper,the station’s deep borehole resistivity observation data from 2016 to 2018 were analyzed in conjunction with some test schemes of the subway.Three kinds of interference characteristics have been found:positive and negative impulse jumping,ascending,and descending.The mechanisms of these changes were briefly discussed.The maximum variation range of surface and deep-well geo-electric observation data was also compared.The results showed that short polar distance observation can minimize subway interference;as the subway line increases,the interference increases correspondingly;subway trial interference operating on geo-electric observation is typically greater than that of formal subway operation.