A Study reffered to the Influence of Heterogeneities in Porous Media on Hydraulic Conductivity and Soil Hydraulic Property

地下水在水資源系統中，占極重要的一環。隨著地下水使用頻率逐年升高，近幾年來，相關模式之研究亦蓬勃發展。而對使用者來說，模式中地下水參數之設定是否合宜，便成為模擬結果成敗之重要關鍵；尤其在現地中，地表下之土層狀況並非均質，異質物於土壤空間分佈及土壤中所含有之異質物之多寡，對地下水流或污染之傳輸影響甚巨，為了能徹底了解異質物對地表下傳輸行為之影響，故本研究遵循達西定律，在不同水力梯度下，分別進行土壤中異質物含量及隨空間分佈不同之定水頭砂箱實驗，以求出土壤之水力傳導係數，並與三維地下水模擬模式VSAFT2(Variably Saturated Flow and Transport utilizing the Modified Method of Characteristics, in 2D)之模擬結果進行比較分析，此外，亦透過模式中模擬水力特性曲線之V.G.公式，來探討非飽和之水力特性曲線。本研究結果顯示：異質物含量增加及排列愈複雜時，其平均水力傳導數會降低，而模式模擬水力傳導係數與實驗之結果比較，兩者最大誤差控制在小數點以下二位，說明該模式在模擬含異質物時之地下水流動具有相當的準確性。The ground water plays an important role in water resources system. The models of ground water are presented more and more by the increasing frequency of using ground water resources. How to set the parameters correctly becomes a key of a successful simulation for users. Especially for In-situ test, the soil characteristics in the subsurface are not homogeneous; the heterogeneities have an enormous influence on the transport of ground water flow or chemical. For this reason, we solve this problem by a constant head sand-box experiment at different hydraulic gradient with heterogeneities in porous media. Then we compare the result with the VSAFT2 model and use the V.G. formula to simulate the hydraulic properties curves. The results reveal that when the heterogeneities increase or the distribution of porous media becomes complicated, the hydraulic conductivity will decreases and the hydraulic properties curves will change. Finally, it can be concluded that the VSAFT2 model is reliable by comparing the results of experiment and model simulation.審定書....................................................I謝.....................................................II文摘要................................................III文摘要.................................................IV錄......................................................V目錄..................................................VII目錄....................................................X一章 導論............................................1.1研究緣起...............................................1.2研究目的...............................................2.3研究流程及步驟.........................................2.4文章架構...............................................3二章 文獻回顧........................................5.1實驗及水力傳導係數之相關研究...........................5.2 VSAFT2模式之相關研究..................................7三章 砂箱模型試驗.......................................9.1砂箱模型試驗...........................................9.1.1定水頭試驗...........................................9.1.2達西定律............................................10.1.3試驗校正-溫度、雷諾數影響因子.......................12.2試驗準備工作..........................................16.2.1土壤基本性質及試驗..................................16.2.2砂箱模型介紹........................................19.2.3透水石..............................................20.2.4水管、量筒及水箱模型................................22.2.5土樣填放及異質物埋設................................24.3試驗流程與步驟........................................26四章 模式理論及應用....................................30.1 VSAFT2模式理論.......................................30.2 VSAFT2模式功能.......................................33.3 VSAFT2模式應用.......................................35 4.3.1VSAFT2模擬砂箱試驗...............................35 4.3.2VSAFT2模擬水力特性曲線...........................38五章 實驗與模式結果....................................41.1土壤基本性質試驗......................................41.2砂箱試驗與飽和模式模擬結果............................43.2.1砂箱試驗結果........................................43.2.2VSAFT2模式模擬結果..................................48.3雷諾數之檢覈..........................................51.4實驗與模式模擬之比較..................................52.5水力特性曲線模擬結果..................................57.5.1均質土壤中且無異質物模擬結果........................57.5.2異質物排列均勻含量10%及20%..........................59.5.3異質物隨機排列含量10%及20%..........................63六章 結論與建議........................................69.1結論..................................................69.2建議..................................................70考文獻.................................................7