(1. 中南大學(xué) 有色金屬成礦預(yù)測教育部重點實驗室，長沙 410083；
2. 中南大學(xué) 地球科學(xué)與信息物理學(xué)院，長沙 410083)
摘 要: 通過有限元法數(shù)值計算，對影響坑道直流聚焦法超前探測距離的主要因素及該方法的超前探測距離進行研究。模擬含水層體積變化、測量電極距變化、異常電阻率比值、坑道旁側(cè)異常體的變化和掘進面后方坑道中的金屬體對超前探測距離的影響。結(jié)果表明：掘進面到含水層的距離、測量極距變化和異常電阻率比值對聚焦法超前探測距離的影響不大，當(dāng)坑道后方存在金屬體時對超前探測距離沒有影響；而坑道正前方目標(biāo)體(含水層)的體積變化對聚焦法超前探測距離的確定影響較大，聚焦法超前探測的有效距離為10~11 m。
關(guān)鍵字: 坑道；聚焦電流法；有限元；超前探測距離
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
