臺灣博碩士論文加值系統

為研究以粗粒徑土壤為背填材料之加勁擋土牆承載強度與變形特性，本研究進行一系列符合平面應變變形模式之回包式牆面加勁擋土模型牆加載試驗。本研究之模型牆體尺寸為183cm(長) ×80cm(寬) ×112cm(高)。本試驗採用30公分寬之剛性條型基礎進行垂直加壓。背填土採用礫石(平均粒徑D50 = 4 mm)，加勁材則採用叁種勁度相異之PET地工格網。為了解擋土牆之變形特性，於加載過程中，除監測擋土牆之垂直承載力與基礎沉陷量外，並藉由影像分析方法以量測土體內部各點之位移與牆面之側向位移，繼而觀測出土體剪裂帶的漸進發展趨勢。研究結果顯示，於相同基礎沉陷量下，加勁礫石擋土牆之垂直承載力較未加勁者明顯增加，且其牆面水平位移量亦較未加勁者顯著地減少。採用抗拉勁度愈大之加勁材之加勁擋土牆的基礎承載力愈大且其牆面側向變形愈小。將影像分析結果所得之格點變形圖、最大剪應變等值圖及零伸張壓縮應變方向向量圖進行相互對照皆可觀察出剪裂帶的漸進式發展趨勢。加勁材的加入將影響擋土牆內部土體之剪裂帶樣式之發展。

In this study, a series of plane strain model tests on wrap-faced geogrid-reinforced soil (GRS) retaining wall bacfilled with gravels were conducted. Three types of geogrids having different nominal strengths were used. The dimensions of the model wall were 183 cm (width) × 80 cm (depth) × 112 cm (height). A strip footing of 30 cm wide, having its setback distance equal to 50cm was located on the surface of backfill to resist the applied vertical load during model test. The vertical pressure and displacement of footing base were measured in the tests. Besides, by using photogrammetric analysis method, the deformation patterns of soil particle, the lateral movement of facing and the progressive failure process of soil based on the calculated shear strain contours were also obtained. The test results indicated that compared to unreinforced soil, the bearing capacity of reinforced gravel was increased. It was found that the higher stiffness of reinforcement the higher value of bearing capacity and lower value of later deformation of facing. The figures of deformed grid point, the contour of maximum shear strain and vector of the zero-extension line of soil all revealed the process of progressive shear failure of retaining wall. The deformation pattern and shear zone area were found to be significantly influenced by the inclusion of reinforcement.

摘要
ABSTRACT
目錄
圖目錄
表目錄
第一章 緒論
1.1研究動機與目的
1.2研究方法
1.3研究內容
第二章 文獻回顧
2.1加勁材及土壤之互制原理
2.1.1直接剪力試驗
2.1.2拉出試驗
2.2 影響加勁土基礎承載力之因素
2.2.1 加勁材埋置基礎下方之深度
2.2.3 填土材料與加勁材開孔
2.2.4基礎退縮距離
2.3加勁擋土牆之模型試驗
2.3.1縮尺模型試驗
2.3.2邊坡模型試驗
2.3.3小型模型試驗
2.4觀測加勁土達破壞之方法
第三章 試驗規劃與試驗方法
3.1模型試驗規劃
3.2加勁擋土牆模型試驗
3.2.1擋土牆模型
3.2.2 MTS垂直油壓加載系統
3.2.3資料擷取系統
3.2.4試驗施作之其他設備
3.2.5觀測擋土牆模型破壞樣式之方法
3.3擋土牆試驗條件
3.3.1背填土性質
3.3.2加勁材
3.3.3擋土牆牆面材料
3.4填築擋土牆之流程
3.4.1填築擋土牆之前置作業
3.4.2擋土牆試體之填築流程
3.4.3試驗儀器相關位置與儀器設定
3.4.4試驗結束後續處理與保養
3.5擋土牆之影像處理與分析
3.5.1消除照片鏡頭弧度偏差
3.5.2各標點位移情形之座標擷取
3.5.3擋土牆之牆面變形量測與分析
3.5.4擋土牆觀測面標點變形之應變量計算
3.5.5擋土牆剪裂帶繪製
第四章 模型試驗結果
4.1基礎承載力曲線
4.2擋土牆剪裂帶發展樣式
4.2.1數位格點變形圖
4.2.2最大剪應變等值圖
4.2.3零伸張(壓縮)應變方向向量圖
4.2.4綜合討論
4.3擋土牆之牆面變形樣式
4.4加載後加勁材之拉出破壞樣式
第五章 結論與建議
5.1結論
5.2建議
參考文獻
附錄A MatLab_Normal True.m
附錄B 影像分析九區域原始圖

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