引江补汉工程是南水北调中线工程的后续工程,可行性研究阶段坝下方案输水隧洞初拟4条线路进行比选,比选线路区地形地质条件和工程地质问题复杂,具有线路长、埋深大,地层岩性复杂多样、可溶岩和软质岩分布较多,地质构造背景复杂、总体地应力水平高等地质特点,深埋长隧洞工程可能涉及的工程地质问题均有可能出现,有必要选择一条地质条件相对较优的线路。经分析研究,将线路比选考虑的地质因素分为关键地质因素、重要地质因素、一般地质因素,并建立多因子条件下的线路比选模型,经工程地质综合比选,龙安1线输水隧洞方案总体较优,地质选线成果为工程设计综合选线提供了重要依据,地质比选研究思路与方法可为同类工程提供借鉴。

The Water Diversion Project from the Three Gorges Reservoir to the Hanjiang River (WDTGH) is a follow-up project to the Middle Route Project (MRP) of the South-to-North Water Diversion (SNWD). During the feasibility study stage, four routes of water conveyance tunnel under the Danjiangkou dam were proposed for comparison based on their topographical and geological conditions and engineering geological problems. The geological conditions of the proposed routes are complex, with long routes, large burial depths, varied formation lithology, abundant dissolvable rocks and soft rocks, complex geological structure background, and high overall geostress levels. Therefore, it is necessary to select a route with relatively good geological conditions to avoid engineering geological problems that may occur in the deep-buried long tunnel project. Through analysis, the geological factors considered in the comparison and selection of the routes were classified into three levels as key geological factors, important geological factors, and general geological factors. A comparison model under the condition of multiple factors was established for comprehensive analysis and comparison on engineering geology. The study reveal that the water tunnel scheme of Long'an Line 1 has overall advantages. Thus, the results of geological route selection provide foundation for comprehensive route selection in engineering design. Additionally, the research ideas and methods of geological comparison and selection can serve as a reference for similar projects.