臺灣博碩士論文加值系統

土壤中的異質物如岩石、大塊礫石等會阻止或減緩降雨的入滲速率而增加土壤的孔隙水壓，而在異質物的表面會產生積水而出現正值的壓力水頭並加快土壤水分飽和速率，這些都會增加邊坡土層的不穩定的因素而造成崩塌或是土體破壞。
保水曲線與水力傳導係數曲線是非飽和孔隙介質的水分傳輸過程中兩個重要且基本的土壤水力特性。自然狀況下土壤中會夾雜著不同成分性質的土壤的異質性土壤，其中異質物的多寡或排列的方式，是如何影響該土壤水力特性為本文探討的重點;另外土柱尺度的大小不同是否亦會影響土壤水力特性是本文另一重點。本研究利用二維地下水模擬模式 (VSAFT2)，來模擬並分析在相同的邊界條件下，均勻異質物排列方式的土柱尺度的大小是否會影響土壤水力特性曲線。研究結果發現，異質性土柱尺度的大小會改變土壤水力特性曲線。在相同的壓力水頭下土柱中隨異質物增加會使含水比逐漸減少；在相同的含水量下，非飽和水力傳導係數會隨異質物增加而逐漸升高。在加入異質物的土柱，在不同的尺度大小、不同的網格數下其平均飽和水力傳導係數會隨著土柱尺度大小的不同而有所改變。

Many researchers have concluded that these hazards were mainly related to the pore pressure variation in unsaturated media. Local heterogeneities in the soil such as rocks and gravels may clog the infiltration and increase the pore pressure or cause ponding on the top of heterogeneities and positive pore pressure. This will increase possibilities of the slope instability and debris flow.
In subsurface porous media, the soil water release curve and unsaturated hydraulic conductivity curve are two important soil hydraulic property curves. The soil water release curve defines the water content as a function of pressure head; and the unsaturated hydraulic conductivity curve establishes relationship between hydraulic conductivities and pressure head or water content. Spatial heterogeneity is ubiquitous in nature, which may significantly affect soil hydraulic property curves. The main theme of this paper is to investigate how spatial heterogeneities, including their arrangement and amount in soil column, affect soil hydraulic property curves.
Using actual soil parameters, this paper used a two-dimensional Variably Saturated folw and solute transport finite element model (VSAFT2) to simulate variations of pressure and moisture content in the soil column under a constant flux boundary condition. Cases of porous media with different proportion of heterogeneities are carried out to investigate the behavior of soil hydraulic property curve owing to variation of heterogeneities and their arrangements.
Results show that the pressure head remains a specific value, the soil moisture decreases while heterogeneities increase in soil column. On the other hand, the unsaturated conductivity increases while heterogeneities increase in soil column when the moisture content remains the same value.

中文摘要 Ⅰ
英文摘要 Ⅱ
誌　　謝 Ⅷ
目 錄 Ⅷ
符號索引 Ⅷ
圖索引 Ⅷ
表索引 ⅩⅠ
第一章 緒論 1
1.1 前言 1
1.2 研究動機 2
1.3 研究目的 4
1.4 研究方法 4
1.5 研究步驟 5
1.6 本文架構 5
第二章 文獻回顧 7
2.1 達西定律 7
2.2 水力傳導係數相關研究 8
2.2.1 Slichter 分析 8
2.2.2 Hazen 分 9
2.2.3 Fair and Hatch 分析 9
2.2.4 Amer and Awad 分析 9
2.2.5 Shahabi,et al.分析 10
2.3 保水曲線(Water retention curve) 10
2.3.1 Brooks-Corey模式﹙BC modle﹚ 11
2.3.2 van Genuchten模式﹙VG modle﹚ 11
2.4 土壤水分傳輸的控制方程式 12
2.4.1 飽和層土壤水分傳輸的控制方程式 12
2.4.2 未飽和層土壤水分傳輸的控制方程式 13
2.5 VSAFT2 數值模擬方程式 16
第三章 異質物對入滲之影響 17
3.1 均質二維土柱 17
3.2 含不規則異質物的二維土柱 21
3.3 單一均質土柱加入異質物之影響結果 24
3.3.1 均質二維土柱 24
3.3.2 含不規則異質物的二維土柱 25
第四章 數值模擬方法 27
4.1 數值實驗項目 27
4.2 數值模擬實驗步驟 30
第五章 結果與討論 32
5.1 單一均質土壤在不同尺度的土柱內模擬 32
5.2 大小相同的模擬土柱內加入數量不同的異質物 43
5.3 大小相同模擬土柱內加入均勻同量排列方式不同的異質物 48
5.4 不同尺度的模擬土柱內加入均勻排列的異質物 50
5.4.1 模擬放大鏡模式 50
5.4.2 模擬試體大小模式 55
5.4.3 模擬單一試體放大模式 58
第六章 結論與建議 61
6.1 結論 61
6.2 建議 62
參考文獻 63
作者簡介 65
授權書 66

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