臺灣博碩士論文加值系統

本研究使用PLAXIS 2D有限元素程式探討台中地區之卵礫石層中，鄰近地下涵洞開挖工程之相關力學行為，以期先掌握施工階段可能遇到的狀況，加以預防並降低擋土開挖可能造成之災害。
本研究模擬了兩種不同地質條件，分別為:(1)地表下3公尺之砂土，下層為卵礫石，地下水位於地表面。(2)地表下7公尺厚的紅土，下層為卵礫石，地下水位於地下8公尺處。又依擋土結構與涵洞邊緣距離分為5m與10m，總共四種案例。
研究結果顯示：(1). 不論開挖工程與涵洞之遠近，開挖完成後之較大變形，對地層情況較佳者發生於涵洞上方地表，而地質較差者發生於第二層支撐背後土壤。(2). 開挖工程與涵洞間之距離由10m減少為5m時，對地層情況較佳者，擋土結構剪力與彎矩分別增加16%與10%，而地質較差者，其增量約5%。(3) 水平支撐系統，不論開挖工程與涵洞之遠近，開挖完成後之最大軸力，對相同地層情況而言，其差異不大，但地質較差者承受較大軸力，尤其最下面第三者層其增量近乎1倍。(4).開挖工程與涵洞之距離由10m減少為5m時，地質情況較差之影響，涵洞變位之影響較剪力與彎矩為大，至於地質情況較佳者，其影響非常少。

This study aims at the relevant mechanical behavior of excavation adjacent to underground culvert in boulder and gravel layer of Taichung area using the PLAXIS 2D finite element program. It is expected that possible situation during the construction can be grasped in advance to prevent and reduce the disaster caused by excavation.
Two different geological conditions are considered, namely: (1). the surface sand is 3m of thickness, the lower is gravel and groundwater is on the ground surface. (2). the red surface soil is 7 m of thickness, the lower is gravel and groundwater is located at 8 m below the surface. Moreover, there are two types of distance between the retaining wall and culvert edge, 5m and 10m. Total four cases are carried for analysis
From the analyzed results, they show that (1). No matter what distance between the retaining wall and culvert edge, the large deformation occurs near the upper surface of culvert for better geological condition, while it is near the backfill of the second layer of horizontal strut for worse geological condition. (2).When the distance between the retaining wall and culvert edge is from 10m reduced to 5m, the shear and moment in the retaining structure is increased 16% and 10% respectively for better geological condition, while they are increased only about 5% for worse geological condition. (3). There is no apparent difference in the maximum axial force of horizontal strut for the same geological condition no matter what distance between the retaining wall and culvert edge. However, the maximum axial force of bottom third layer of horizontal strut is increased 100% for the worse geological condition compared with that of better geological condition. (4). When the distance between the retaining wall and culvert edge is from 10m reduced to 5m, the deformation of culvert is increased more significantly than the shear and moment, while it is less for all in better geological condition.

中文摘要 i
ABSTRACT ii
目錄 iii
表目錄 vi
圖目錄 vii
第一章 緒論 1
1.1 前言 1
1.2 研究動機與目的 2
1.3 研究方法 3
1.4 研究內容 4
第二章 文獻回顧 5
2.1 卵礫石土層性質 5
2.2紅土性質 6
2.3 台中卵礫石土層擋土構造形式 7
2.4深開挖擋土壁體之變形特性 9
2.5 有限元素方法 10
2.6涵洞 12
第三章 分析方法 15
3.1分析程式介紹 15
3.1.1輸入(Input) 15
3.1.2計算(Calculation) 16
3.1.3輸出(Output) 17
3.2網格生成 18
3.3輸入材料參數 19
第四章　研究範例分析 22
4.1研究範例 22
4.1.1案例模型 22
4.1.2材料參數 25
4.1.3分析步驟 27
4.2 研究範例一 28
4.3 研究範例二 42
4.4 研究範例三 56
4.5 研究範例四 70
4.6 研究範例分析結果比較 84
第五章　結論與建議 86
5.1結論 86
5.2建議 87
參考文獻 88

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