(1. 中南大学 有色金属成矿预测教育部重点实验室，长沙 410083；
2. 中南大学 地球科学与信息物理学院，长沙 410083)
摘 要: 通过有限元法数值计算，对影响坑道直流聚焦法超前探测距离的主要因素及该方法的超前探测距离进行研究。模拟含水层体积变化、测量电极距变化、异常电阻率比值、坑道旁侧异常体的变化和掘进面后方坑道中的金属体对超前探测距离的影响。结果表明：掘进面到含水层的距离、测量极距变化和异常电阻率比值对聚焦法超前探测距离的影响不大，当坑道后方存在金属体时对超前探测距离没有影响；而坑道正前方目标体(含水层)的体积变化对聚焦法超前探测距离的确定影响较大，聚焦法超前探测的有效距离为10~11 m。
关键字: 坑道；聚焦电流法；有限元；超前探测距离
DC focus resistivity in tunnel by finite element method
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
Central South University, Changsha 410083, China;
2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China）
Abstract:By finite element method, the focus of DC method detection distance influence factors and the valid detection distance were studied. The effects of the aquifer bed volume variation, the range of potential electrode, the ratio of anomalous resistivity and the metallic anomalies existing behind the tunnel face on the advanced detection distance were simulated. The results indicate that the distance between the tunnelling surface and aquifer bed, the range of potential electrode and the ratio of anomalous resistivity have a slight influence on the detection distance, meanwhile, the effect of the metallic anomalies existing behind the tunnel is not obvious. However, the detection distance can be affected greatly by the volume variation of the target (the aquifer bed) right ahead the tunnel, and effective detection range is 10−11 m.
Key words: tunnel; DC focus method; finite element method; advanced detection distance
