臺灣博碩士論文加值系統

在降雨情況下，不飽和土壤邊坡由於降雨入滲，土壤基質吸力隨含水量的增加而下降，降低不飽和土壤剪力強度，造成邊坡破壞的發生。而許多邊坡破壞案例中，凹坡是為主要的破壞地形。目前不飽和土壤力學的研究領域中，多以分析應用及力學性質實驗作為主要的研究重點，尚未清楚地探討地形效應對於不飽和土壤邊坡的影響。
本研究藉由量測降雨前後之現地不飽和土壤基質吸力(Matric suction)及體積含水量(Volumetric Water Content)的方式，分別以濾紙法（Filter paper method）及張力計（Tensiometers）量測土壤基質吸力，並配合水份計之土壤體積含水量的量測，於凸坡(Ridgelike slopes)、平面坡(Flat slopes)及凹坡(Gullied slopes)三種填方坡之不同邊坡位置(上邊坡、中間邊坡及邊坡坡趾)，量測土壤基質吸力及體積含水量之變化情況，以探討降雨情況下邊坡地形對於不飽和土壤力學特性之影響。
本研究結果顯示，基質吸力隨邊坡位置的下降而降低，表示邊坡越下方所受由上而下的逕流影響就大。此外，凹坡地形由於易集水之幾何條件，使得邊坡各位置之基質吸力相較於凸坡及平面坡是最小的。就凸坡及平面坡而言，凸坡之上邊坡、中間邊坡及邊坡坡趾之基質吸力下降量是較平面坡之相對位置小的，表示平面坡受到由上而下的逕流影響較凸坡嚴重。基質吸力越大，不飽和土壤剪力強度就會越高，表示凸坡的穩定性是較平面坡佳的，而凹坡最差。

During rainfall,the rainfall water infiltrates into the unsaturated soil slope which results in an increase in soil water content,a decrease in soil matric suction and a decrease in shear strength to tigger the slope failures.At present,the research field of the unsaturated soil mechanics focused on application analysis and mechanics experiment,rather than influence from slope topography to the near-ground characteristics.
The matric suctions and volumetric water content of the soil along the depth at the upper and lower part of the slope were measured prior to and after the rainfall event.The matric suctions of the soil at a depth of 1.2m, 1.5m, and 2.7m were measured using jet-filled tensiometers, and those at a depth of 0.15m, 0.6m, and 0.9m were measured using the filter paper method because the matric suctions at the shallow depth were expected to be high and tensiometers are only capable of measuring the matric suction up to 90kPa;the volumetric water content is determined by the soil water monitoring in the backfill slopes of three different terrains(ridgelike slopes,flat slopes,and gullied slopes) and slope positions(up-slope,mid-slope,and toe),to find out the changes on matric suction and volumetric water content.Also it explores the influence of slope topography on the near ground characteristics of unsaturaterd soils subjected to rainfall.
The results show that,the matric suction is reduced with the decline of slope position，show slope the more influence flowed by runoff from top to botton.In addition,make the matric suction is the smallest of the ridgelike slopes and the flat slopes.As regards ridgelike slopes and flat slopes,drop of matric suction of slope position in difference of ridgelike slope is apparently smaller than flat slope，i.t.,ridgelike slope is influenced the more seriously that the flat slope is flowed by runoff from top to bottom.The unsaturated shear strength rise to increase with the matric suction,the stability of the ridgelike slope is that relatively the flat slope is good and the gullied slope is the worst.

中文摘要 I
Abstract III
誌謝 VI
目錄 VII
表目錄 XII
圖目錄 XIV
第一章、緒論 1
1-1、前言 1
1-2、研究動機與目的 2
1-3、研究內容簡介 4
第二章、文獻回顧 6
2-1、不飽和土壤之組成 6
2-2、不飽和土壤基質吸力之理論 9
2-3、土壤水份特性曲線 15
2-4、土壤性質對基質吸力之影響 19
2-4-1、體積含水量之影響 20
2-4-2、滲透係數之影響 20
2-4-3、孔隙比之影響 21
2-4-4、塑性指數之影響 22
2-5、基質吸力與不飽和土壤剪力強度之關係 23
2-6、降雨入滲對基質吸力之影響 35
2-6-1、降雨強度對基質吸力之影響 36
2-6-2、降雨延時對基質吸力之影響 37
2-7、地形因素對基質吸力之影響 38
第三章、研究方法與流程 49
3-1、量測區域概況 50
3-1-1、選定量測場址及現場概況描述 50
3-1-2、量測區域之土壤性質及分佈 51
3-1-3、量測區域氣候概況 52
3-2、研究方法及流程 53
3-3、量測儀器組成及其使用方法 56
3-3-1、張力計（Tensiometers） 56
3-3-1-1、簡介 56
3-3-1-2、張力計量測原理 57
3-3-1-3、張力計裝設方法及步驟 58
3-3-2、濾紙法（Filter Paper Method） 59
3-3-2-1、簡介 59
3-3-2-2、濾紙法試驗原理 62
3-3-2-3、濾紙的品質 63
3-3-2-4、總吸力與基質吸力之率定曲線 65
3-3-2-5、濾紙法試驗步驟 69
3-3-3、土壤水分測定 71
3-3-3-1、土壤水份計之簡介 71
3-3-3-2、土壤水份計之測定原理 72
3-3-3-3、土壤水份計裝設步驟及量測方法 72
第四章、實驗結果探討與分析 102
4-1、降雨事件描述 102
4-2、基質吸力與體積含水量量測歷時結果探討 105
4-2-1、基質吸力歷時結果探討 105
4-2-1-1、凸坡(Ridgelike slopes)基質吸力量測歷時結果 106
4-2-1-2、平面坡(Flat slopes)基質吸力量測歷時結果 109
4-2-1-3、凹坡(Gullied slopes)基質吸力量測歷時結果 112
4-2-2、體積含水量歷時結果探討 113
4-2-2-1、凸坡之體積含水量測歷時結果 114
4-2-2-2、平面坡之體積含水量測歷時結果 116
4-2-2-3、凹坡之體積含水量測歷時結果 117
4-3、土壤水分特性曲線(Soil Water Characteristic Curve) 118
4-4、地形效應探討 122
4-4-1、邊坡形狀對於基質吸力變化的影響 122
4-4-1-1、各坡形之上邊坡對基質吸力影響比較 122
4-4-1-2、各坡形之中間邊坡對基質吸力影響比較 123
4-4-1-3、各坡形之邊坡坡趾對基質吸力影響比較 126
4-4-2、邊坡位置對基質吸力變化之影響 129
4-4-3、累積降雨量與入滲深度的關係 133
4-5、基質吸力貢獻剪力強度與基質吸力之關係 137
第五章、結論與建議 192
5-1、結論 192
5-2、建議 195
參考文獻 196
附錄A 208
附錄B 216
附錄C 224

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