摘要
隧道工程建设可破坏施工区的地下水平衡,引发地下水疏降以及其他生态环境问题。文章以某引水隧道为研究对象,基于隧道周边水库蓄水量明显减少的问题,采用水文地质调查、示踪试验等方法,查明补径排条件变化特征,分析引水隧道工程与周边地下水之间的水力联系及其对周边水库蓄水量变化的影响。引水隧道施工过程中,周边3km范围内有12处泉点呈疏干或半疏干状态,且隧道南西侧泉点受影响程度较北西侧小。基于解析法计算可知引水隧道开挖后对地表水及地下水的影响半径范围为649~2073m,影响面积为13.7km^(2),与水库集水范围重叠面积为4.02km^(2)。野外示踪试验结果表明引水隧道上部地表落水洞与引水隧道排水口、部分泉点之间存在密切的水力联系,水库的部分补给水源改向隧道口径流和排泄,致使水库蓄水量减少。研究结果表明引水隧道工程建设改变了周边地下水补径排条件,从而导致水库水源不足,蓄水量减少,影响了城市居民供水。
Tunnel construction can disrupt the groundwater balance,impacting the drainage of both surface water and groundwater,as well as causing other eco-environmental effects.This study takes a water-diversion tunnel as the research object.Prompted by a pronounced decline in the storage of the adjacent reservoir of the tunnel,it integrates hydrogeological surveying and tracer tests to characterize the altered recharge–flow–discharge conditions,elucidate the hydraulic interactions between the tunnel and the surrounding groundwater system,and quantitatively evaluate the tunnel’s impact on the observed reservoir-storage variations.Field investigations indicate that groundwater in the study area can be divided into three categories:karst water from carbonate rock fissures,karst water from fissures characterized by carbonate rock interbedded with clastic rock,and karst water from pores and fissures characterized by mudstone interbedded with silty mudstone.The water bearing formations of karst water from carbonate rock fissures consist of the Lower Triassic Jialingjiang Formation(T_(1)j)and the Daye Formation(T_(1)d^(3+4))along the axis and wings of an anticline.These units exhibit significant water abundance and are well developed with karst landforms,such as karst depressions,sinkholes,caves,and underground rivers.Karst water from fissures characterized by carbonate rock interbedded with clastic rock occurs within the first and third members of the Middle Triassic Badong Formation(T_(2)b^(1+3))along the axis and wings of a syncline.The water abundance of the formation is moderate,and karst features are only locally developed.Karst water from pores and fissures characterized by mudstone interbedded with silty mudstone is primarily stored in the second member of the Middle Triassic Badong Formation(T2b2)and exhibits comparatively low water abundance.Groundwater recharge is derived primarily from atmospheric precipitation and surface water bodies such as reservoirs and fish ponds.Due to the large terrain cutting,the speed of surface water runoff is fast.The catchment of the reservoir is located west of the axis of the water-diversion tunnel on the southeast wing of the anticline.Exposed strata comprise limestone,dolomitic limestone,dolomite,and rock-solution breccia of T_(1)j and T_(1)d^(3+4),as well as limestone,argillaceous limestone,argillaceous dolomite,and mudstone of T_(2)b.Within the Jialingjiang and Daye Formations,sinkholes,depressions,and dissolution fissures are well developed,facilitating efficient infiltration of rainwater through karst conduits to the saturated zone.Although karst development is weak in the Badong Formation,secondary structures have intensely fractured the rock mass;rainwater recharge,therefore,occurs dominantly through fissures.Overall,the catchment exhibits favorable groundwater recharge conditions.After infiltration,groundwater migrates southwestward along either longitudinal karst conduits or fissure networks.The deeply cut watercourse in which the reservoir is located,along with the dense network of tributary gullies,ultimately leads to the discharges of groundwater in the form of karst springs within these gullies.The water-diversion tunnel crosses the anticline,traversing limestone and dolomite of T1d and T1j,with T_(1)j serving as the principal aquifer.The anticlinal axis functions as a watershed,resulting in the southern and northern segments of the tunnel each forming an independent groundwater system.The tunnel site is deeply cut,resulting in poor recharge conditions.Scattered precipitation accumulates only within the upper narrow peak-cluster depressions,subsequently infiltrating vertically along sinkholes.Southwest of the tunnel,the reservoir catchment consists of T1j,T1d,and T_(2)b formations,which are characterized by well-developed sinkholes,karst depressions,and corrosion fissures that create favorable discharge conditions.Following rainfall events,groundwater is directed southwestward along longitudinally oriented karst conduits.These conduits are cut by gullies,where groundwater ultimately discharges as karst springs.Before the construction of the water-diversion tunnel,atmospheric precipitation infiltrated through surface karst depressions,sinkholes,dolines,or corrosion fissures to recharge groundwater.Afterward,a portion of the precipitation flowed through the aquifer and discharged in the form of an underground river along the riverbank.Another portion of flowed through the runoff that crossed fissures perpendicular to the structural trend,and discharged in the form of karst springs(including the S01 spring point)or underground rivers within the gully and watercourse that cut the south-eastern wing of the anticline.The spring points exposed in the gully and watercourse were the main source of water supply for the reservoir.Because the water-diversion tunnel intersected the transition zone between the vertical and horizontal circulation cells of the karst aquifer,its excavation repeatedly intersected underground rivers and cave systems.Severe water inflows were encountered,resulting in twelve springs within a 3-km radius becoming either completely or partially dewatered.Springs located to the southwest of the tunnel were less affected than those to the northwest.Analytical calculations indicate that the influence radius of the water-diversion tunnel on surface water and groundwater extends from 649 to 2,073 m,covering 13.7 km^(2).The overlapping area of the reservoir catchment is 4.02 km^(2).Tracer tests confirm a strong hydraulic connection between the surface sinkholes located above the tunnel,and the drainage outlet of the water-diversion tunnel and several spring points.Consequently,a portion of the reservoir’s recharge has been diverted to runoff at the tunnel exit and subsequently discharged,thereby reducing the storage capacity of the reservoir.The findings demonstrate that the alteration of regional groundwater recharge–flow–discharge conditions induced by the tunnel project is the primary cause of the observed decline in groundwater-derived inflow to the nearby reservoir.
作者
温金梅
吴涛
李娴
江晨
陈立
刘胜
蒙丽
WEN Jinmei;WU Tao;LI Xian;JIANG Chen;CHEN Li;LIU Sheng;MENG Li(No.208 Hydrogeology and Engineering Geology Team,Chongqing Bureau of Geology and Mineral Exploration and Development(Chongqing Institute of Geological Hazard Prevention Engineering Investigation and Design),Chongqing 400700,China;College of Civil Engineering,Hefei University of Technology,Hefei,Anhui 230009,China;College of Environment and Ecology,Chongqing University,Chongqing 400045,China)
出处
《中国岩溶》
北大核心
2025年第3期500-509,共10页
Carsologica Sinica
基金
重庆市长江经济带1∶5万奉节幅、巫山幅水文地质调查(ZC-2021109(21C01730))
国家自然科学青年科学基金项目(42107082)
安徽省自然科学基金项目(2108085QD166)。
关键词
隧道工程建设
地下水
蓄水量
影响
示踪试验
tunnel projects
groundwater
storage capacity of the reservoir
influence
tracer test
