【作者】 毛正君；

【导师】 杨晓华；

【作者基本信息】 长安大学 ， 岩土工程， 2013， 博士

【摘要】 工程建设的安全、经济与对工程设施周围环境的保护是工程建设工作面对的三大问题。“安全”、“经济”和“环保”是对立统一的矛盾体，如何使它们相互协调，是摆在每位工程师面前的难题。乌鞘岭隧道群区域处于多种脆弱生态区的过渡地带。然而，隧道却修建于地下水最为活跃的地壳表层。隧道施工将使其成为地表水、地下水汇集场所或新的排泄通道，进而影响隧道施工安全和破坏隧道所在区域生态环境。本文通过区域地下水环境现场观测与区域三维渗流场数值模拟，分析了乌鞘岭隧道群区域地下水运移特征，从而就隧道群施工引起地下水运移的生态环境效应进行了定量化评价，并提出了基于乌鞘岭隧道群施工引起的地下水运移特征的长效防排水措施，主要研究成果如下：1.通过野外调研及系统总结前人研究成果，归纳出乌鞘岭隧道群区域环境地质特征，从自然地理、区域地质、区域水文地质及生态环境四个方面进行阐述，该区域地形与地貌类型复杂，地质构造复杂，岩性岩相变化大，地质环境条件复杂，生态环境脆弱。2.通过对乌鞘岭隧道群区域地下水环境现场观测，即土壤水分动态观测和地下水位动态观测，确定了乌鞘岭隧道群区域植物与土壤水分动态变化的关系：植被生长与潜水关系不大，而主要受大气降水以及土壤水分动态变化的影响；各植被类型土壤含水量的变异系数随土壤深度的增加呈递减的变化趋势，即埋深越深，其土壤含水量变化剧烈程度越小；时间特征上呈现出明显的季节性变化，可将其划分为失水期、聚水期、退水期和稳水期；土壤水分可以通过植物的蒸腾作用、土壤地表直接蒸发和土壤水分汇流后的蒸发作用散失，而土壤水分恢复，只有大气降水一种途径。3.建立了乌鞘岭隧道群区域三维渗流场数值模拟概念模型及数学模型，采用MODFLOW软件，进行了隧道群区域三维渗流场数值模拟。根据多年平均降水量资料，通过建立隧道开挖前计算区多年平均条件下非稳定流模型，计算得到乌鞘岭隧道群区域地下水初始流场。隧道施工对地下水渗流场的影响主要受各地层渗透性和隧道排水高差控制。根据计算结果，随着隧道施工进度的推进，地下水位下降幅度逐渐增大，降落漏斗除沿隧道走向逐渐发展外，向隧道两侧也逐渐扩展。预测乌鞘岭隧道群竣工十年时，各隧道潜水位均有所恢复。4.通过工程类比法及考虑乌鞘岭隧道群区域具体情况，建立了乌鞘岭隧道群施工引起地下水运移的生态环境效应评价指标体系，该指标体系由自然地理、区域地质、生态环境和隧道施工四个子系统组成。自然地理子系统包括坡度、坡向、绝对高程、多年平均降雨量、多年平均蒸发量。区域地质子系统包括断层破碎带发育程度、褶皱发育情况。生态环境子系统包括土壤类型、植被覆盖度。隧道施工子系统包括隧道长度、隧道建筑限界净宽、隧道施工方法、隧道最大埋深、隧道防排水设计。采用简单关联函数确定各指标权重，并基于物元可拓模型，综合评价了乌鞘岭隧道群施工期引起地下水运移的生态环境效应，判定乌鞘岭隧道群施工期生态环境效应属于等级2，即较弱，但偏向于等级3，即中等（严格来说，应属于等级2.581）。5.针对位于高寒脆弱生态区的乌鞘岭隧道群，依据对乌鞘岭隧道群区域地下水运移特征的研究成果，提出相应的隧道围岩注浆堵水措施、结构防水措施和排水系统设置及其具体技术参数。更多还原

【Abstract】 Engineering construction is faced with three major problems: the safety of engineeringconstruction, the economy of engineering construction, the protection of environmentsurrounding engineering facilities.“Safety”,“economy” and “environmental protection” arethe body of the unity of opposites. How to make them mutual coordination is every engineer’sproblem. Wushaoling tunnel group is located at transition zone of many fragile ecologicalregions. However, this kind of tunnel is constructed on the crustal derm of the most activegroundwater. The construction will make the tunnel become influx place of surface water andgroundwater, or become a new discharge passage, which will influence the safety of tunnelconstruction and destroy ecological environment. Through field observation of regionalgroundwater environment and regional three-dimentional seepage field numerical modeling,we analyze the characters of regional groundwater movement, make quantitative evaluationon the eco-environmental effect of groundwater movement caused by tunnel groupconstruction, and put forward long-acting waterproof and drainage measures on the charactersof regional groundwater movement. Main research results are as follows:1. Through field investigation and systematically summarizing predecessors’ researchresults, the paper summarizes regional environmental geological characters of Wushaolingtunnel group from four aspects: physical geography, regional geology, regional hydrogeology,ecological environment. In this region, the types of terrain and landform are complex.Geological structure is complex. Lithology and lithofacies greatly change. Geologicalenvironmental conditions are complex. Ecological environment is fragile.2. Through field observation on regional groundwater environment of Wushaoling tunnelgroup, that is including dynamic observation on soil moisture and groundwater level, weconfirm relationship between plant and soil moisture dynamic variation. Plant growth, whichis mainly influenced by meteoric water and soil moisture dynamic variation, has littlerelationship with phreatic water. The variance coefficient of various plant types’s soilmoisture decreases with increasing of the soil depth in the region. The buried depth is deeper,the variation of soil moisture is less. Time feature shows obvious seasonal variation, whichcan be divided into water loss, water collection, recession flow, and water stability. The lossof soil moisture can get through plants transpiration, soil surface direct evaporation andevaporation after soil moisture confluence. However, supplying soil moisture only has oneway of meteoric water. 3. Based on creating conceptual model and numerical simulation of three-dimensionalseepage field, we use MODFLOW to achieve three-dimensional seepage field numericalsimulation. According to the data of long year average precipitation, creating unsteady flowmodel under long year average condition before tunnel construction, we calculate and getregional groundwater initial flow field. Tunnel construction has an influence on groundwaterseepage field, which is controlled by different formation permeability and tunnel drainage’sheight difference. According to calculation, with the promotion of tunnel construction process,the decrease of groundwater level gradually increases. Cone of depression also graduallyextends to two sides of tunnel, except that it gradually develops along tunnel trend. WhenWushaoling tunnel group will have been completed for ten years, each tunnel phreatic waterlevel will recover a little.4. According to engineering analogy and actual situation of the region of Wushaolingtunnel group, we create the index system of eco-environmental effect evaluation caused bygroundwater movement in the construction period of Wushaoling tunnel group. Thisevaluation index system contains four subsystems: physical geography, regional geology,eco-environment, tunnel construction. The subsystem of physical geography contains slope,aspect, absolute height, annual average precipitation, and annual average evaporation. Thesubsystem of regional geology contains fault fracture zone development degree, folddevelopment. The subsystem of eco-environment contains soil types, vegetation coverage.The subsystem of tunnel construction contains length of tunnel, structural approach limitwidth of tunnel, tunnel construction method, tunnel max buried depth, design of tunnelwaterproof and drainage. According to matter element extension model, we use simplecorrelation function to confirm every index weight and comprehensively evaluate theeco-environmental effect caused by groundwater movement in the construction period ofWushaoling tunnel group. Eco-environmental effect is judged belongs to grade two, that isweaker. But it is partial to grade three, that is medium. Strictly speaking, it belongs to grade2.581.5. Aiming at Wushaoling tunnel group which is located at alpine fragile environment,based on research results on the characters of regional groundwater movement of Wushaolingtunnel group, we propose corresponding specific technical parameters of grouting forstopping up water in rock mass, structure waterproofing, drainage system setting.更多还原