瞬变电磁法指导复杂地质隧道超前水平钻探应用

The application of TEM to guiding advance exploration drilling of complex geological tunnel

云南山区地质条件复杂,隧道施工中经常发生突泥涌水等地质灾害。隧道超前地质预报是预防隧道施工地质灾害的重要手段。合理布置和实施超前水平钻孔,可以有效地揭示隧道掌子面前方的地质情况,预防重大突泥涌水地质灾害的发生。但对岩溶等不规则地质体,有限的1～2个超前水平钻孔不一定能揭示出这些地质体,给隧道施工造成重大安全风险。充分利用物探超前预报资料,特别是瞬变电磁法对突泥涌水等低阻地质体敏感的特性,指导超前水平钻孔的布置,对提高超前水平钻孔的预报效果有重要意义。本文以玉磨铁路扬武隧道为例,通过瞬变电磁法资料分析,指导超前水平钻孔布置,再与钻孔和施工开挖结果进行对比分析,说明瞬变电磁法预报和指导超前水平钻孔是有效的,并对今后瞬变电磁法结合超前水平钻孔进行隧道超前地质预报工作提出了建议。

Geological conditions in Yunnan mountainous area are complex,and geological hazards such as water and mud inrush often occur in tunnel construction.Tunnel geological prediction is an important way to prevent geological disasters in tunnel construction.The rational layout and implementation of advance exploration drilling can effectively reveal the geological conditions in front of the tunnel face and prevent the occurrence of geological disasters.Nevertheless,for the irregular geological bodies such as karst,the limited 1~2 advance exploration drilling holes sometimes fail to reveal these geological bodies and cause major safety risks to the tunnel construction.It is of great significance to make full use of the advanced geophysical prediction data,especially the TEM which can guide the layout of the advance exploration drilling holes and have the great significance for improving the prediction effect.In this paper,taking the Yangwu tunnel of Yumo railway as an example and based on the analysis of TEM,the authors successfully guided the advance exploration drilling layout,and then compared the results with the drilling and construction excavation results.It is shown that the TEM is effective in predicting and guiding the advance exploration drilling.Some suggestions are given concerning the employment of TME combined with advanced horizontal drilling in the future.