臺灣博碩士論文加值系統

土壤滲流沖蝕行為為地下水滲流而產生滲流力，驅使邊坡顆粒產生移動之情形，可能造成邊坡開始發生破壞之現象。由實驗結果發現滲流發生時，土壤顆粒隨著地下水水流被帶出，逐漸於邊坡下緣淘刷，發生蝕洞現象，使邊上方土體失去支撐而崩落，故為了進一步減少因地下水滲流沖蝕引發之邊坡穩定之問題，對邊坡沖蝕行為有其了解的必要性。
一般滲流沖蝕行為之模擬都以室內砂箱模型為主，雖然有許多相關之實驗研究結果，但往往受到模型尺度的影響以及實驗環境的限制，有時甚至很難以實驗的方法得到良好的結果。本研究希望藉由數值方法模擬室內砂箱模型之破壞發生的過程，探討滲流沖蝕破壞的機制，將來可更有效地應用在大尺度的工程研究上。
本研究採用分離元素法之數值軟體－PFC2D進行滲流沖蝕之模擬。PFC2D之數值軟體，顆粒流本是一種連續之過程，利用此優點，結合滲流力之定義，合理模擬實驗之結果。最後，由數值軟體模擬結果發現，可獲得與實際試驗結果相似之滲流沖蝕行為，完整呈現滲流沖蝕行為之過程，如滲流初期產生之蝕洞現象、邊坡上方土體失去支撐而崩落及不同水頭所造成的不同破壞規模。

Seepage erosion behavior is due to groundwater seepage force. Groundwater seepage force moves slope soil particles, and therefore slope failure occurs potentially. According to previous experimental results, we found soil particles flow out from the slope after groundwater seepage started. Flowing of soil particles caused soil scouring and cavitation occurred at slope toe. The slope soil particles on cavitation location collapsed because of the loss of support. To decrease slope failure problems due to soil seepage erosion, we need to learn more about soil seepage erosion behavior.
Simulation of soil seepage erosion behavior is mainly based on sandbox test. Although there are many researches about seepage erosion behavior, the results indicate that sandbox tests are usually affected by the model sizes and experimental situations. We use numerical methods to simulate experimental results and study the mechanism of seepage erosion.
In this study, we use PFC2D which is based on the discrete element method to simulate soil seepage erosion behavior. Particle flow is a continuous process, which is an advantage to simulating soil seepage erosion behavior with groundwater seepage force. Our results successfully simulate sandbox tests and show that the process of soil seepage erosion completely. It offers a new method which is easier and cheaper to simulate soil seepage erosion behavior and complete process and results.

摘要 i
Abstract ii
目錄 iii
表目錄 v
圖目錄 vi
第一章 前言 1
一、 研究動機與目的 1
二、 研究流程 2
三、 論文架構 2
第二章 文獻回顧 4
一、 滲流沖蝕之定義 4
二、 砂箱實驗模擬 5
三、 未飽和土壤之抗剪強度 10
第三章 材料與方法 12
一、 分離元素法之數值軟體PFC2D 12
二、 有限元素法之數值軟體PLAXIS 2D 15
三、 試驗材料 17
第四章 研究結果 22
一、 滲透試驗 22
二、 有限元素軟體PLAXIS 2D分析結果 25
三、 材料參數之校正 31
四、 PFC2D滲流沖蝕試驗 38
第五章 結論與建議 50
一、 結論 50
二、 建議 50
參考文獻 52

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