隧洞突涌水指示西南岩溶大泉成因关系及水环境效应分析

Indications of tunnel water inrush to the origin of large karst springs in Southwest China and water environmental effects

滇中引水工程昆呈隧洞横穿昆明市呈贡区主要的水源地——黑龙潭、白龙潭地区,隧洞涌水可能严重威胁城市供水安全。综合隧洞施工水文动态数据和水化学数据,分析岩溶水系统特征和隧洞施工的影响,论证两泉的成因关系;构建了昆呈隧洞黑龙潭—白龙潭段三维地下水流模型,经模型识别验证后,开展隧洞施工条件岩溶水系统的流场和泉流量变化的模拟预测,分析评价其水环境效应。研究表明:黑龙潭与白龙潭分别属于相对独立的2套岩溶水系统,补给区均为P_(1)q+m组强岩溶含水层,但在三家村洼地下游,两泉分别受P_(1)d组隔水地层和浑水塘断层的控制而形成稳定的岩溶通道;昆呈隧洞掘进改变了区域地下水流场,并袭夺白龙潭泉流量使其断流,且泉流量恢复困难;但隧洞掘进对黑龙潭影响较小。本研究对岩溶泉的成因关系进行探讨,并定量分析隧道掘进的水环境影响,对防止岩溶地区隧道建设中的突涌水等问题具有参考借鉴意义。

[Objective]The Kuncheng Tunnel of the Central Yunnan Water Diversion Project crosses the Heilongtan and Bailongtan areas,the major headwater regions in the Chenggong District of Kunming City.[Methods]Tunnel water inrush may seriously threaten the safety of the urban water supply.In this paper,based on hydrodynamic data and hydrochemical data during tunnel construction,the characteristics of the karst water system,the origin of the springs,and the impact of tunnel construction were analysed.Then,a three-dimensional groundwater flow model for the Heilongtan-Bailongtan Section was developed and calibrated to simulate and predict groundwater level changes during the construction of the Kuncheng Tunnel,and the water environment effect of tunnel construction was evaluated.[Results]The results show that both the Heilongtan and Bailongtan springs are mainly recharged by the same karst P_(1)q+m aquifer.However,controlled by aquitard P_(1)d and the Hunshuitang fault downstream of the Sanjiacun Depression,the two springs actually belong to two relatively independent karst water systems.In addition,the excavation of the Kuncheng Tunnel has changed the regional groundwater flow field and cut off the flow of Bailongtan,while it has negligible impact on Heilongtan.[Conclusion]This study discusses the genetic relationship of karst spring,and quantitatively analyzes the impact of tunnel excavation on water environment,which has reference significance for preventing water inrush in tunnel construction.