臺灣博碩士論文加值系統

非飽和層土壤為一多相態系統，系統內流體的流動與溶質傳輸機制非常複雜難以掌握，其流動與傳輸機制主要受控於非飽和土壤的水力特性，而土壤保水曲線的獲得為求取土壤水力傳導係數的主要途徑之一，因此，土壤保水曲線在非飽和層水文特性研究中扮演非常重要之角色。傳統上，保水曲線皆在穩定的狀態下獲得，並直接將其應用於現地的土壤水文特性的分析。然而，現地環境並非處於一穩定狀態，近年來的研究顯示，由靜態條件所獲得的保水曲線並無法完整描述現地動態環境的土壤特性，所獲得之水力參數代表性將有所存疑。因此，為了解動態效應對土壤保水曲線之影響，並量化其與毛細壓力及飽和度間之關係，本研究利用GS#40與GS#80石英砂進行一系列的砂箱實驗，藉由調整不同邊界條件以獲得動態與靜態之試驗結果。此外，利用RETC軟體針對砂箱實驗結果進行靜態保水曲線模擬及van Genuchten模式參數擬合，以靜態保水曲線為基礎，探討不同的邊界條件下，不同粒徑大小之地質材料對於保水曲線動態效應之影響，並討論動態係數與重新分布時間之差異。研究結果顯示，靜態條件與動態條件下之保水曲線差異明顯，於給定的飽和度下，土壤在排水過程中，動態條件下的毛細壓力高於靜態條件下的毛細壓力，而濕潤過程則相反。動態係數與重新分布時間計算結果，在中間飽和度區間數值較低，而在高飽和度與低飽和度區域則有較高數值。地質材料之粒徑差異對動態係數與重新分布時間之影響，在排水過程中有較顯著之差異，而注水過程差異則相對不明顯。對於本研究實驗之動態效應，推論可能的物理機制包含水的滯留、空氣滯留、接觸角效應以及毛細管半徑（粒徑大小）。雖然各種機制之影響程度仍尚未完全釐清，有待更進一步之驗證，然而動態效應對於保水曲線之影響將可以被肯定，未來對於非飽和層水力參數之計算則必須將其納入考量。

Unsaturated soil is a multiphase system in which the mechanisms of groundwater flow and solute transport are complicated. These mechanisms are mainly dominated by the relative hydraulic conductivity and the estimate of the hydraulic conductivity can be accomplished with the soil water retention curve (SWRC). Therefore, SWRC plays an important role when hydraulic properties in the unsaturated zone are investigated. Traditionally, SWRCs are usually obtained under static or steady-state water flow condition and the dynamic effects are not considered. However, the real system always changes. The SWRC obtained under equilibrium condition cannot completely represent the variations of the system and the estimated hydraulic conductivity remains skeptical. Therefore, the objective of this study is to understand the influence of dynamic effects on the unsaturated soil and to quantify its relations to the capillary pressure and saturation. In this study, a series of sandbox experiments were conducted by using GS#40 and GS#80 quartz-sands under different boundary conditions to obtain various SWRCs. Besides, RETC software is used to fit the static SWRC and van Genuchten model’s parameters, and the magnitude of dynamic coefficient and redistribution time are calculated. The dynamic effect on SWRC due to different boundary conditions and different particle sizes are investigated, and their influence to dynamic coefficient and redistribution time are also discussed. The results show that the SWRC obtain under static condition and dynamic condition are different. At the given saturation, dynamic capillary pressure is larger than static capillary pressure during the drainage process. On the contrary, the dynamic capillary pressure is lower than static capillary pressure during the imbibition process. The calculated results indicate that both of dynamic coefficient and redistribution time are relatively small within the range of intermediate saturation and are higher at the endpoint of saturations. Moreover, the influence of different particle sizes on the dynamic coefficients is more significant during the drainage process than that during the imbibition process. According to the dynamic effect presented in this study, four potential physical mechanisms, i.e., water entrapment, air entrapment, contact angle effect, and radius of capillary tube (particle size) are addressed. Although the individual influence of these potential mechanisms on dynamic effect still remains unknown and the further verification are required, its influence on SWRC has been confirmed and cannot be ignored when quantifying the unsaturated hydraulic properties.

致謝 I
摘要 II
Abstract III
目次 IV
圖次 VI
表次 IX
一、緒論 1
1.1 前言 1
1.2 研究動機與目的 1
1.3文獻回顧 2
1.4研究流程及架構 5
二、研究方法 7
2.1土壤保水曲線 7
2.2遲滯效應 9
2.3動態效應 11
2.4影響動態效應機制 13
2.5重新分布時間 14
2.6保水曲線擬合 15
2.6.1 Brooks-Corey模式（BC模式）16
2.6.2 van Genuchten模式（VG模式）16
三、實驗室砂箱實驗 20
3.1實驗儀器與地質材料 20
3.2砂箱設計 22
3.3 砂箱實驗步驟 24
3.4砂箱實驗結果 25
3.4.1 GS#40實驗結果 25
3.4.2 GS#80實驗結果 29
3.4.3 GS#40與GS#80結果比較 32
四、動態效應量化分析 37
4.1保水曲線擬合 37
4.2動態係數計算 42
4.3重新分布時間計算 50
4.4粒徑大小與動態係數及重新分布時間比較 57
4.5儀器置放位置與動態係數及重新分布時間比較 59
4.6動態效應機制探討 61
五、討論 65
六、結論 71
七、參考文獻 73

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