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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/5321

    Title: 高滲透性含水層微水實驗 壓力反應之分析;Analysis of Depth-Dependent Pressure Head of Slug Tests in Highly Permeable Aquifers
    Authors: 吳季蓉;Ching-Rung Wu
    Contributors: 水文所
    Keywords: 深度修正;微水實驗;振盪;高滲透性含水層;data analysis;highly permeable aquifers;slug test;depth-dependent pressure head
    Date: 2005-05-12
    Issue Date: 2009-09-22 09:51:29 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 在高滲透性非受壓含水層進行微水實驗(slug test)時,若井中水位面落在井篩段之間;則水位回升會造成有效井篩長度隨著時間而改變,此種現象稱為部分浸水(partially submerged)。部分浸水的壓力特徵呈現非振盪曲線特徵;濾料補水時會呈現折線,無濾料補水時會呈現一負斜率直線。因有效井篩長度隨著時間而改變,需利用合適的方法來修正紀錄到的水位壓力,本次研究比較利用無修正水位壓力的模式分析,得到的結果會低估徑向水力導數(horizontal hydraulic conductivity)22%。而當半對數圖上產生下凹曲線特徵時,則表示為有效井篩長度隨時間變化太大所造成,建議避免實驗時初始水位過大或壓力計擺放深度過深。若井中水位面落在井篩之上,稱為全部浸水(fully submerged),則會產生振盪曲線特徵。本次研究建立深度修正標準曲線疊套方法,由於使用第一個水頭極大值位置來代替真正的初始水位,所以標準曲線壓力頭在開始的前三秒壓力頭比微水實驗資料極大值來的小,但卻不影響分析結果。利用水頭發生極大值與極小值的各時間點和振盪週期,來驗證標準曲線疊套決定所得到的參數和結果,獲得到相同的答案。當使用未考慮深度影響的模式分析,標準曲線疊合振盪資料無法完全疊合,亦會低估徑向水力導數結果,表示全部浸水狀態下,井中動態壓力水頭需考慮深度的影響;利用深度修正來分析振盪資料結果較為正確。 Abstract Analysis of pressure head of slug Tests in highly permeable aquifers. Slug tests have two conditions in the well. Partially submerged is the static water table located in the screen and sand pack. Fully submerged is the static water table is situate above both the screen and sand pack. The recharge curve exhibits log-liner form partially submerged screen and sand pack conditions. The effective length of screen changed follow time, need using applicable model to correcting pressure head. If is not to correct pressure head, horizontal hydraulic conductivity will be underestimated 28%. When a curve exhibits down-concave, express what the effective length of screen changed too much follow time. It is suggested that the initial well water displacement be less and the pressure transducer is placed at depth not close to the well bottom. At fully submerged conditions, a curve matching method is presented for the analysis of oscillatory pressure head that is dependent on depth. The Springer and Gelhar (1991) solution and a depth correction relation are used to generate dimensional type curves of pressure head versus time. A trial-and-error procedure is established to find the type curve best fitting the field data by adjusting the two unknown parameters, the horizontal hydraulic conductivity and the effective length of well water column. Analytical relations for some oscillation characteristics of the converted pressure head are derived, and they are useful in checking accuracy of the estimates. A field example is given to demonstrate this curve matching method, and it indicates that the true initial well water displacement is important to the data analysis. It is suggested that the actual initial well water displacement be determined, especially when the pressure transducer is placed at depth not close to the initial well water level.
    Appears in Collections:[水文與海洋科學研究所] 博碩士論文

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