黄陵背斜东北翼岩溶水系统特征及其对引调水隧洞工程的影响

黄陵背斜东北翼地层以碳酸盐岩和碎屑岩相间的组合形式出现，碳酸盐岩分布区岩溶发育强烈，岩溶突涌水是该区地下工程建设的重要影响因素。以某重大引调水工程黄陵背斜段为研究对象，综合采用岩溶水文地质调查、示踪试验、水文地球化学等多种方法对研究区岩溶水系统特征及隧洞突涌水条件进行了识别和分析。结果表明：区内存在4个子含水系统，垂向上构成了透水性强-弱相间的结构，发育了浅部快速循环、中间快速循环和深部慢速循环的多级水流系统，断裂构成各子含水系统间发生水力交换的垂向通道。工程输水隧洞主体在深部灯影组(Z₂dn)和天河板组-石龙洞组(∈₁t+sl)子含水系统中穿越，岩溶发育总体较弱，但在穿越店垭断裂时存在导通上部娄山关组-南津关组(∈₃l-O₁n)强岩溶子含水系统而发生较大规模高压突涌水的可能。施工支洞穿越∈₃l-O₁n子含水系统中白龙洞水流系统的排泄区，遭遇管道式突涌水事故的风险高。多种水文地质方法的联合解译可提高识别岩溶水系统特征和突涌水条件的精度。

Characteristics of the karst water system on the northeast wing of the Huangling anticline and its impact on water diversion tunnel engineering

The strata in the northeast wing of the Huangling anticline consist of interbedded carbonate rocks and clastic rocks. As the carbonate rocks underwent strong karstification, karst water inrush would be a significant factor impacting the construction of underground engineering in this area. Taking the Huangling anticline section of a critical national water diversion project as the research object, the characteristics of the karst groundwater system and the water inrush conditions in tunnels were identified by various methods, such as karst hydrogeological surveys, tracer tests and hydrogeochemistry analysis. These results show that the aquifer system contains four sub-aqueous systems with a structure of strong and weak permeable interlayers in the vertical direction, in which a multi-stage karst groundwater system has developed with shallow rapid circulation, intermediate rapid circulation and a deep slow circulation subflow systems. The faults constitute the vertical channels for hydraulic exchange between sub-aquifer systems. The water diversion tunnel primarily crosses the deep Dengying Formation (Z₂dn) and Tianheban-Shilongdong Formation(∈₁t+sl) aquifer systems with weak karst development. However, a large-scale high-pressure water inrush accident may occur when passing through the Dianya fault, which may transfer groundwater from the upper karst sub-aquifer system of the Loushanguan Formation-Nanjinguan Formation (∈₃l-O₁n) into the tunnel. The risk of encountering conduit water inrush accidents is high during construction when the construction branch tunnel passes through the discharge area of the Bailongdong groundwater flow system in the ∈₃l-O₁nsub-aquifer systems. The accuracy of identifying of karst groundwater flow system features and inrush conditions can be improved by joint interpretation of multiple hydrogeological methods.