中文摘要：

对坑道超前探测方法中的三维坑道直流聚焦法的电极组合作了研究。计算、分析了2个同性点电源的电流分布规律,指出由于电流的相互排斥作用,电流密度在这两个点电源的中垂线下一定深度处产生最大值,这个深度与这两个点源之间的距离成正比。基于上述理由,设计出3种电极组合：四点电源、五点电源和九点电源布极方式。用三维有限单元数值模拟的方法计算了上述3种电极系的空间电位分布,发现九点电源方式对电流聚束效果较好,而且当主电极电流小于屏蔽电极电流时效果最好。

英文摘要：

In tunnel advanced exploration, the lateral focusing resistivity method has become a common method in logging. The authors carried out researches on the electrode assemblage of the three-dimensional tunnel DC focusing method. Based on the calculation and analysis of the current distribution regularity of two like point electric sources, this paper points out that, due to the mutual repelleney of the current, the current density will produce the maximum value at a certain depth below the perpendicular-bisector of the two point electric sources, and this depth is in direct proportion with the distance between the two point sources. On such a basis, the authors designed three kinds of electrode assemblages, i.e. four-point electric sources, five-point electric sources and nine - point electric sources. Then, the three-dimensional finite element digital simulation method was used to calculate the spatial potential distribution of these three electrode systems. The results show that the nine-point electric source type can yield fairly good current beam bunching effect and, moreover, the effect of the current seems to be the best when the current of the principal electrode is lower than the current of the shielded electrode.