金属护栏对洛阳地震台地电阻率干扰定量分析

自2018年12月起，因洛阳地震台测区内安装金属护栏，该台地电阻率出现异常变化。为正确评估此次影响，结合洛阳地震台电测深曲线、岩性资料建立了三维水平层状结构模型，利用有限元法计算了测区内金属护栏对洛阳地震台地电阻率观测的影响。同时，建立典型“H”型电性结构模型，分析了不同属性的金属导线对地电阻率观测的影响。结果显示：①金属护栏是洛阳地震台此次地电阻率年变异常的主要影响因素。当位于测区内影响系数为负的区域时，金属护栏引起地电阻率的趋势性上升；当位于影响系数为正的区域时，金属护栏引起地电阻率的趋势性下降。②不同属性的金属导线对地电阻率观测的影响不同。导线与测道夹角减小、导线长度增加、导线电阻率减小以及导线横截面积增加等均会导致干扰源对地电阻率年变影响作用增强。

Quantitative analysis of the interference of metal barriers on the geoelectrical resistivity observation at Luoyang Seismic Station

Since the end of 2018, the geoelectrical resistivity observation at Luoyang seismic station appeared abnormal changes due to the installation of metal barriers. In order to correctly evaluate the impact, this paper establishes a 3D horizontal layered structure model based on electrical sounding curves and lithology data of Luoyang Seismic Station and quantitatively calculates the dynamic impact of metal barriers on Luoyang geoelectrical resistivity observation in the survey area by using the finite element method. At the same time, a typical H-type electrical structure model is established to analyze the dynamic influence of different attributes of metal wires on the geoelectrical resistivity observation. The results show that:①the metal barrier is the main factor affecting the annual variation of geoelectrical resistivity observation at Luoyang station. In the area where the influence coefficient is negative, the geoelectrical resistivity observation shows an increasing trend due to the metal barrier. In the area where the influence coefficient is positive, the geoelectrical resistivity observation shows a decreasing trend due to the metal barrier. ②Different properties of metal wires have different effects on the geoelectrical resistivity observation. The influence of interference sources on the annual variation of geoelectrical resistivity observation will be strengthened with the decrease of the angle between the conductor and the observation trace, the increase of the conductor length, the decrease of the conductor resistivity, and the increase of the cross-sectional area of the conductor.