發(fā)布時間：2018-08-20 18:20

【摘要】：地下水數(shù)值模擬的不確定性分析,一直是水文地質學家和研究者研究的重點和難點。本論文旨在通過研究鉆孔數(shù)量、鉆孔分布不確定性對模擬結果的影響,探討水文地質鉆孔布設的依據(jù)；通過對水文地質參數(shù)場進行趨勢化研究,提升鉆孔稀缺地區(qū)地下水流數(shù)值模擬的精度；選用變差函數(shù)分析結合克里格插值的方法研究鉆孔數(shù)量和分布對模擬的影響,；利用蒙特卡羅等方法實現(xiàn)對參數(shù)場的趨勢化處理。將上述研究應用于大興迭隆起地區(qū)區(qū)域地下水流數(shù)值模型,并對大興迭隆起地下水流模型的斷層性質和滲透系數(shù)場進行了不確定性分析。為研究樣本數(shù)據(jù)對模型模擬結果的影響,針對大興迭隆起地區(qū)第四系沉積條件,構建了由3種巖性(滲透性)分布組成的算例模型,三種巖性分別為粗砂、中粗砂和中細砂,其對應的滲透系數(shù)分別為40m/d的、30m/d和20m/d。構建的算例模型剖分為50行×50列,單元格大小為100m×100m的二維潛水穩(wěn)定流模型。通過分析樣本量與巖性場模擬結果可知,在本算例尺度下,模擬誤差在樣本量增加的前期有著快速明顯的下降,在樣本量增加至300后,誤差下降速度迅速減緩,樣本數(shù)達到1000后,誤差基本達到穩(wěn)定狀態(tài)。通過分析樣本位置對巖性場模擬的影響可知,在本算例中樣本量相同的情況下,隨機平均采樣時的巖性模擬結果較為理想,模擬平均誤差約為5.4%；以最鄰近指數(shù)(NNI)表示樣本的聚集程度,研究表明非均勻采樣的模擬誤差隨最鄰近指數(shù)(NNI)的增加而減小。當最鄰近指數(shù)大于0.9后,模擬誤差將小于10%。利用蒙特卡羅方法對滲透系數(shù)場進行趨勢化處理,使?jié)B透系數(shù)場符合二維線性分布。對比隨機滲透系數(shù)場與趨勢化滲透系數(shù)場的模擬結果顯示：兩種方法的水流模擬結果基本相同,而趨勢化滲透系數(shù)場可降低模擬整體誤差1/2左右,模擬誤差較大的地方基本集中在抽水井附近。在滲透系數(shù)場趨勢化處理的基礎上,利用Ucode軟件可以對滲透系數(shù)場進行進一步的優(yōu)化,優(yōu)化后模擬誤差最多可下降1/3左右。大興迭隆起地區(qū)主要由松散孔隙潛水含水層、松散孔隙承壓含水層、奧陶系、寒武系及青白口系灰?guī)r巖溶裂隙含水層組成,巖溶含水層含水介質以裂隙、溶隙為主,具有北方巖溶的特征地下水流動狀態(tài)仍符合達西定律。本次研究建立了大興迭隆起地區(qū)5層非均質、垂向各項異性、空間三維結構、非穩(wěn)定的地下水流數(shù)值模型。在此基礎上,通過改變模型邊界參數(shù)以及趨勢化處理滲透系數(shù)場的方法對模型存在的關鍵問題進行了不確定分析。結果表明：區(qū)內(nèi)的南苑-通縣斷裂基本可以斷定為阻水斷裂,而模型西北的永定河斷裂側向隔水,而在垂向上形成第四系含水層補給巖溶含水層的補給通道。對第四系含水層滲透系數(shù)場進行處理后,在含水層顆粒較粗的地區(qū),滲透系數(shù)變化范圍較廣,趨勢化后模擬精度提升明顯；而在巖性為細砂和粘土的區(qū)域模擬水位值變化十分微弱,趨勢化處理對擬合結果影響較小。
[Abstract]:Uncertainty analysis of groundwater numerical simulation has always been the focus and difficulty of hydrogeologists and researchers. This paper aims to study the number of boreholes, the influence of uncertainty of borehole distribution on the simulation results, and to explore the basis for the layout of hydrogeological boreholes. The accuracy of numerical simulation of groundwater flow in the area with scarce holes is studied. Variation function analysis combined with Kriging interpolation is used to study the influence of the number and distribution of boreholes on the simulation. Monte Carlo method is used to realize the trending treatment of parameter field. Uncertainty analysis of fault property and permeability coefficient field of groundwater flow model in Daxing-stack uplift is carried out. In order to study the influence of sample data on the simulation results of the model, an example model consisting of three lithology (permeability) distributions is constructed for the Quaternary sedimentary conditions in Daxing-stack uplift area. The three lithologies are coarse sand, medium coarse sand and coarse sand. The numerical model is divided into 50 rows by 50 rows, and the cell size is 100 m by 100 m. The simulation results of sample size and lithologic field show that the simulation error is rapid and obvious in the early stage of sample size increase. When the sample size increases to 300, the error decreases rapidly, and the error reaches a stable state after the sample size reaches 1000. By analyzing the influence of sample location on lithology field simulation, we can see that the lithology simulation results are ideal when the sample size is the same, and the simulation average error is relatively good. When the nearest neighbor index is greater than 0.9, the simulation error will be less than 10%. Monte Carlo method is used to trend the permeability field to make the permeability field conform to two-dimensional. The simulation results of the random permeability field and the trend permeability field show that the simulation results of the two methods are basically the same, while the trend permeability field can reduce the overall simulation error by about 1/2. The larger simulation error is concentrated near the pumping well. Basically, the permeability field can be further optimized by Ucode software, and the simulation error can be reduced by about 1/3 after optimization. The Daxingtai uplift area is mainly composed of unconsolidated pore phreatic aquifer, unconsolidated pore confined aquifer, Ordovician, Cambrian and Qingbaikou limestone karst fissure aquifer, and karst aquifer aquifer aquifer aquifer aquifer aquifer aquifer aqui The groundwater flow state with the characteristics of karst in the north still conforms to Darcy's law. In this study, a five-layer numerical model of heterogeneous, vertical anisotropy, three-dimensional structure and unsteady groundwater flow in Daxing-Die uplift area was established. On this basis, the seepage was treated by changing the boundary parameters of the model and trending. The results show that the Nanyuan-Tongxian fault in the area can be basically regarded as a water-blocking fault, while the Yongdinghe fault in the northwest of the model is lateral water-blocking, and the Quaternary aquifer is vertically formed to recharge the karst aquifer. After the permeability field is processed, the variation range of permeability coefficient is wider in the area with coarser aquifer particles, and the simulation precision is improved obviously after trending, while the variation of simulated water level is very weak in the area with fine sand and clay, and the trending treatment has little influence on the fitting result.
【學位授予單位】：中國地質大學(北京)
【學位級別】：博士
【學位授予年份】：2016
【分類號】：P641

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