研究目的：艰险山区地质条件复杂,勘察期间难以详尽查明艰险山区隧道的工程地质问题,导致施工期间揭示的地质情况与勘察成果存在一定差异,勘察精度不能满足艰险山区隧道建设的需要。依托艰险山区5条铁路隧道工程已有勘察成果与施工资料,通过分析隧道建设过程中存在的围岩变更、重大地质条件变化、工期延误与投资超概问题,对艰险山区复杂地质铁路隧道地质勘察现状进行分析与总结,以期提高艰险山区复杂地质铁路隧道勘察精度。
研究结论：（1）导致隧道施工期间揭示地质情况与勘察成果存在差异的主要勘察原因是勘察周期设计不合理、勘探点布置不合理、地下水以及软岩大变形识别精度不足;（2）基于此提出了调整勘察周期、优化勘探点布置、高压富水带精细化评价以及高地应力环境软岩大变形分级的对策;（3）本研究成果可为艰险山区复杂地质隧道工程地质勘察工作提供借鉴。

Research purposes: The geological conditions in the difficult mountainous area are complicated, and it is difficult to find out the engineering geological problems of the tunnel in the difficult mountainous area in detail during the survey, which leads to some differences between the geological conditions revealed during the construction and the survey results. The survey accuracy can not meet the needs of tunnel construction in difficult mountainous areas. Based on the existing investigation results and construction data of five railway tunnel projects in the difficult mountainous area, this paper analyzes and summarizes the geological investigation status of the complex geological railway tunnel in the difficult mountainous area by analyzing the surrounding rock changes, major geological condition changes, construction delay and investment overestimation problems existing in the tunnel construction process, in order to improve the accuracy of the complex geological railway tunnel investigation in the difficult mountainous area.
Research conclusions: （1）The main investigation reasons leading to the difference between the revealed geological conditions during tunnel construction and the predicted conditions during the investigation are unreasonable design of the investigation period, unreasonable arrangement of exploration points, insufficient understanding of groundwater and large deformation of soft rock.（2） Based on this, the countermeasures of adjusting the survey period, optimizing the layout of exploration points, fine evaluation of high pressure rich belt and large deformation classification of soft rock in high ground stress environment are put forward.（3）The research results can provide reference for geological survey of complex geological tunnels in difficult mountainous areas.