臺灣博碩士論文加值系統

本文研究目的為探討連續壁槽溝破壞之土楔形狀與穩定性問題，研究對象為均質無凝聚性砂質土壤之連續壁槽溝。與破壞土楔研究相關之模型砂箱試驗顯示：(1) 破壞滑動面為一弧形曲線；(2) 足夠的導牆尺寸可使地表面不發生塌陷。因此本文在破壞土楔形狀研究方面，針對導牆影響與否提出三維槽溝破壞土楔分析法。研究方法首先將槽溝開挖解壓而導致之應力重新分佈考慮為垂直與水平兩方向之土壤拱效應，破壞土楔的形狀則是依土壤拱效應作用下之主應力軌跡與Mohr-Coulomb破壞準則決定。同時藉由數值分析軟體FLAC3D分析結果驗證本文所建立之三維破壞土楔形狀。確立破壞土楔形狀後則以極限平衡分析觀念，發展連續壁槽溝開挖之三維穩定分析理論並探討各主要影響參數之影響效果。
結論顯示：應用土壤拱效應理論，配合Mohr-Coulomb破壞準則中主應力旋轉概念，可模擬出三維連續壁槽溝之破壞土楔形狀。其次，以數值分析體FLAC3D，進行槽溝破壞模擬。並將本文分析法、數值分析結果與砂箱模型試驗結果相互比較可得：不論在土楔破壞形狀或槽溝穩定性方面皆顯示本文分析法具有較佳的預測精度。另外，針對實際工程使用方面，將極限平衡分析成果轉化為圖表形式，經誤差比較後，此圖表適用於估計地表面破壞範圍與槽溝穩定之安全因數。

The main purpose of this research is to study the collapse wedge and the stability behind trenches supported by slurry in cohesionless soils. According to the previous laboratory experiments, the failure behind the trenches can summarized as: (1) trench failure initiates with the sliding of a shell-shaped wedge; (2) if the penetration depth of the guide wall is enough, no cave-in appears on the ground surface when the trench will collapse. Therefore the sliding of collapse wedges in this research is different by the effect of guide wall. The analytical approach is developed by considering the arching effects both in the vertical and horizontal direction. A shell-shaped slip surface of the sliding soil mass is defined by the Mohr-Coulomb criterion and the factor of safety is defined by the limiting equilibrium. Results of this study show that the proposed method can get the more accurate shell-shaped wedge after comparing with a scale model test and numerical simulation using FLAC3D. In addition, also can get better results of trench stability than other analytical methods. Finally by the analytical approach can arrange as charts, which are useful to estimate the collapse range and the stability behind slurry trenches.

誌謝 I
摘要 II
目錄 III
表目錄 V
圖目錄 VI
符號說明 XI
第一章 緒論 1
1-1 研究動機與目的 1
1-2 研究內容與方法 1
1-3 本文內容組織與架構 2
第二章 文獻回顧 4
2-1 無限槽溝破壞土楔形狀 4
2-2 土拱效應理論 4
2-2-1 Terzaghi的土壤拱效應理論 5
2-2-2 Handy的土壤拱效應理論 7
2-3 有限槽溝破壞土楔形狀 9
第三章 三維破壞土楔形狀研究 22
3-1 極限邊界 23
3-2 三維破壞土楔形狀模擬 27
3-2-1 XZ平面上的土體破壞邊界 27
3-2-2 YZ及XY平面上的土體破壞邊界 28
3-3 導牆對槽溝穩定性之影響 30
3-3-1 壓力拱 30
3-4 導牆影響下之三維破壞土楔形狀模擬 31
3-4-1 YZ平面上的土體破壞邊界 31
3-4-2 XY及XZ平面上的土體破壞邊界 35
第四章 數值模擬驗證 47
4-1 數值分析工具介紹 47
4-2 數值模擬分析 48
4-2-1 材料及幾何參數 48
4-2-2 分析步驟 50
4-3 數值分析與討論 50
4-4 理論方法，數值模擬與試驗結果比較 51
第五章 破壞土楔穩定分析法 63
5-1 穩定分析 63
5-1-1 土柱元素 63
5-1-2 安全因數計算 65
5-1-2-1 覆土重之計算 65
5-1-2-2 滑動面反力之推求 66
5-1-2-3 地下水壓 69
5-1-2-4 計算安全因數 69
5-1-3 參數研究 70
5-1-4 綜合比較 72
5-2 圖表整理 73
5-2-1 利用圖表求得地表面的破壞範圍 73
5-2-2 利用圖表求得安全因數FS 74
5-2-3 計算例 75
第六章 結論與建議 102
6-1 結論 102
6-2 建議 103
附錄A 104
附錄B 110
參考文獻 123

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