中文摘要：

采用有限元数值方法，计算了对称四极装置观测时测区介质对地电阻率观测的三维影响系数分布。计算结果表明，表层介质整体影响系数为正和为负时，表层介质各区域影响系数的分布形态相近，不同层状电性结构三维影响系数分布形态也相似。在地表二维平面，影响系数在供电电极和测量电极之间存在近似椭圆的负区域，其余区域影响系数为正。沿测线垂直剖面，影响系数在供电电极和测量电极之间存在近似半椭圆的负区域，其余区域影响系数为正。在三维空间上，观测系统布设于地表时影响系数为负的区域位于供电电极和测量电极间的近似半椭球区域，影响系数在靠近电极附近显著大于其余区域。在测区地表局部介质电阻率发生变化时，可依据影响系数分布定性地分析其对地电阻率观测的影响，为进一步实验和数值模型定量分析提供参考。

英文摘要：

We calculate three-dimensional sensitivity coefficients distribution of apparent resistivity observation when Schlumberger array is used by using finite element method. Analysis results suggest that for the situation of one-dimensional positive or minus coefficient of surface medium, three- dimensional sensitivity coefficients distribution at surface shows similar patterns, and sensitivity coefficients distributions of different layered electric structures are also similar. There are two approximate ellipses at the two-dimensional surface plane between current electrodes and potential electrodes, where sensitivity coefficients are minus, and sensitivity coefficients at other areas are positive. Sensitivity coefficients at two approximate ellipses between current electrodes and potential electrodes are minus at the vertical section along monitoring line, while others are positive. From the three-dimensional view, minus sensitivity coefficients are at the two approximate half ellipsoids between current electrodes and potential electrodes when arrays are applied at surface. And coefficients near the electrodes are much greater than other areas. When resistivity of local areas at surface changes, we can qualitatively analyze the disturbing effects caused by the areas using three dimensional sensitivity coefficients distribution, and the analysis result can serve as reference for further experiment and numerical model quantitative analysis.