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研究生: 康文瑋
Kang, Wen-wei
論文名稱: 邊坡之基礎承載力分析
Analysis of ultimate bearing capacity of rigid footing placed on the slope
指導教授: 黃景川
Huang, Ching-chuan
學位類別: 碩士
Master
系所名稱: 工學院 - 土木工程學系
Department of Civil Engineering
論文出版年: 2007
畢業學年度: 95
語文別: 中文
論文頁數: 102
中文關鍵詞: 承載力邊坡
外文關鍵詞: bearing capacity, slope
相關次數: 點閱:186下載:6
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  • 摘 要
    目前,關於位於邊坡上基礎受到地震力影響時承載力表現的分析或經驗公式並不多,故本研究針對坐落於斜坡上之剛性基礎以嚴密Janbu切片法作擬靜態分析求得地震時的承載力係數Nγ ,並將基礎受到傾斜載重、土體受到水平慣性力之影響定出修正係數,以常見的坡角、載重傾斜角經驗公式決定本研究之公式模式。另外顯示出水平地盤上基礎於地震時分析得到之Nγ 、修正係數與其他研究互相比較,其值和文獻中所提及之Nγ、修正公式均有相同的趨勢,而且公式計算值和分析值幾乎相同,所以利用這些公式可以估計靜置於坡肩的剛性基礎於地震時的極限承載力。
    另外也對基礎後退時Nγ 上升情形分析,得到不受坡角影響的距離和後退時之修正係數,以此可以計算剛性基礎在符合所需求的承載力下其安全距離為何,提高其安全性。

    ABSTRACT
    At present, analytical or empirical formula for seismic bearing capacity of footings adjacent to the slope is rather limited. This study uses a pseudo-static-based approach in conjunction with rigorous Janbu’s slice
    method to derive analytical values of seismic bearing
    capacity factors (Nγ) and correction factors for the effects of inertia of soil mass and load inclinations for a rigid footing adjacent to the slope. It is shown that both
    the bearing capacity factors (Nγ) and the correction
    factors for the seismic bearing capacity of footings placed on level ground derived herein are comparable with those reported in the literature. Empirical equations regarding the effects of slope angles and load inclinations,expressed using generalized forms of those proposed in the literature, are also derived. It is also found that the empirical equations derived in the present study provide
    values of correction factors in good agreements with the analytical ones,
    indicating the validity of using these empirical equations for assessing the bearing capacity of rigid footings
    situated on the slope subjected to pseudo-static seismic loading.

    目 錄 摘 要..................................................... I ABSTRACT ................................................ II 致 謝................................................... III 目 錄.................................................... IV 表 目 錄............................................... VIII 圖 目 錄................................................. IX 第一章 緒論............................................... 1 1-1 前言.................................................. 1 1-2 研究目的.............................................. 2 1-3 研究方法及內容........................................ 3 第二章 文獻回顧........................................... 5 2-1 基礎承載力理論........................................ 5 2-2 平地基礎之承載力理論.................................. 6 2-2-1 Terzaghi (1943) 淺基承載力理論...................... 6 2-2-2 Meyerhof (1963) 極限承載力理論...................... 8 2-3 邊坡基礎之承載力...................................... 9 2-3-1 Meyerhof (1963)邊坡承載力........................... 9 2-3-2 Hansen (1970)、Vesic (1973)承載力理論............... 9 2-3-3 Graham et al.(1988)之邊坡承載力.................... 10 2-3-4 邊坡承載力修正建議 (Bowles,1988) ................. 11 2-4 相關研究及試驗....................................... 12 2-4-1 Kusakabe et. al (1981)之基礎承載力試驗............. 12 2-4-2 位於砂質邊坡之基礎穩定分析......................... 13 2-4-3 嚴密Janbu 切片法之應用............................. 13 第三章 程式流程與分析條件................................ 27 3-1 承載力破壞機制假設................................... 27 3-2 分析流程與基礎環境設定............................... 28 3-2-1 基礎極限承載力之推導式............................. 28 3-2-2 程式求解基礎極限承載力之流程....................... 32 3-3 數據之分析與整理..................................... 33 3-3-1 基礎位於不同條件下之Nγ 和比較..................... 34 3-3-2 經驗公式之建立與驗證............................... 34 第四章 坡肩基礎之承載力分析.............................. 39 4-1 平地基礎之極限承載力................................. 40 4-2 坡肩基礎之Nγ −Ι:(α ≥ 0°,β=0°,kh=0) ............. 41 4-2-1 坡角修正係數ηs ................................... 42 4-2-2 ηs 之迴歸分析..................................... 43 4-3 坡肩基礎之Nγ -Ⅱ:(α ≥ 0°,β ≥ 0°,kh=0) ........ 44 4-3-1 載重傾斜角修正係數ηi.............................. 45 4-3-2 ηi 之迴歸分析..................................... 46 4-4 坡肩基礎之Nγ -Ⅲ:(α ≥ 0°,β=0°,kh ≥ 0) .......... 47 4-4-1 水平慣性力修正係數ηe ............................. 47 4-4-2 ηe 之迴歸分析..................................... 48 4-5 坡肩基礎之Nγ -Ⅳ:(α ≥ 0°,β ≥ 0°,kh ≥ 0) ........ 49 4-5-1 水平地震力修正係數ηie ............................ 50 4-5-2 水平地震力修正係數ηie=ηi.ηe .................... 51 4-5-3 ηie 之迴歸分析.................................... 51 4-6 迴歸值準確度評估和公式整理.......................... 52 4-6-1 迴歸值準確度評估.................................. 53 4-6-2 經驗公式整理與驗證................................ 53 第五章 坡頂基礎具退縮距離之承載力分析................... 79 5-1 退縮基礎之Nγ ....................................... 79 5-1-1 基礎退縮修正係數ηb ............................... 80 5-1-2 ηb 之迴歸分析..................................... 81 5-2 坡頂基礎Nγ 與坡肩埋入基礎Nγq 之比較................. 82 第六章 結論與建議........................................ 95 6-1 結論................................................. 95 6-2 建議與後續研究....................................... 96 參考文獻................................................. 98 自 述................................................... 102 表 目 錄 表2-1 Meyerhof(1951)承載力修正係數....................... 16 表4-1 基礎靜置於水平地表和垂直載重下之Nγ比較............ 54 表4-2(a) 基礎位於坡肩時Nγ 比較(φ = 30°);Nγ 為分析值... 54 表4-2(b) 基礎位於坡肩時Nγ 比較(φ = 40°);Nγ 為分析值.... 55 表4-3(b) 坡角修正係數比較(φ = 30°) ..................... 55 表4-3(b) 坡角修正係數比較(φ = 40°) ..................... 55 表4-4(a) 平地基礎受傾斜載重時Nγ 比較(φ = 30°);Nγ 為分析值....................................................... 55 表4-4(b) 平地基礎受傾斜載重時Nγ 比較(φ = 40°);Nγ為分析值....................................................... 56 表4-5(a) 載重傾斜角修正係數比較(φ = 30°) ............... 56 表4-5(b) 載重傾斜角修正係數比較(φ = 40°) ............... 56 表4-6 土體受水平慣性力作用下修正係數比較,()內為迴歸值... 56 表4-7(a) 平地基礎地震時Nγ 比較(φ = 30°);Nγ 為分析值.... 57 表4-7(b) 平地基礎地震時Nγ 比較(φ = 40°);Nγ為分析值... 57 表4-8 平地基礎受地震力之修正係數比較,()內為迴歸值....... 58 表4-9 Nγ 修正係數之經驗公式整理......................... 58 表5-1 基礎後退修正係數ηb 之經驗公式..................... 84 表5-2 Nγ、Nγq 比較 (φ=40°) .................................................... 84 圖 目 錄 圖2-1 Terzaghi 極限承載理論破壞面 (Das) ................. 17 圖2-2 極限承載理論破壞面 (Meyerhof,1951) ............... 17 圖2-3 Hansen(1970)、Vesic(1973)承載力修正係數 (Bowlws,1988) ....................................................18 圖2-4(a) 坡面基礎之承載力破壞面示意圖 (Meyerhof,1957) .. 19 圖2-4(b) 坡頂基礎之承載力破壞面示意圖 (Meyerhof,1957) ...19 圖2-5(a) 承載力係數和坡角關係圖 (Meyerhof,1957) ........ 20 圖2-5(b) 承載力係數和基礎後退關係圖 (Meyerhof,1957) .... 20 圖2-6(a) 坡頂基礎之相關位置和破壞面示意圖 (Graham,1988) .21 圖2-6(b) Nγq (a)D/B=0;(b)D/B=0.5;(c)D/B=1.0 (H/B=0、0.5);(Graham,1988) .....................................22 圖2-6(c) Nγq (a)D/B=0;(b)D/B=0.5;(c)D/B=1.0 (H/B=1、2); (Graham,1988) .......................................... 23 圖2-7(a) Terzaghi、Meyerhof 破壞機制比較 (Bowles,1988).. 24 圖2-7(b) 邊坡基礎之相關位置和破壞面示意圖 (Bowles,1988)..24 圖2-8 邊坡斜面上基礎之破壞機制 (Kusakabe,1981) ......... 25 圖2-9 由模型試驗假設之破壞機制 (Huang and Tatsuoka,1994) 25 圖2-10 嚴密Janbu 切片法示意圖 (Huang and Tatsuoka,1994) 26 圖3-1 承載力破壞機制示意圖............................... 35 圖3-2 邊界條件和切片作用力概念圖......................... 36 圖3-3 程式求解基礎極限承載力流程圖....................... 37 圖3-4 本研究之流程....................................... 38 圖4-1 平地基礎承載力係數Nγ 與其他學者比較圖............. 59 圖4-2 不同分析方法求得之承載力係數Nγ 與坡角α關係圖...... 60 圖4-3 基礎位於坡肩受α影響下之破壞面示意圖............... 42 圖4-4(a) 坡角修正係數ηs 與坡角α之關係圖和迴歸公式比較... 61 圖4-4(b) 參數a 與φ 之關係圖和迴歸公式................... 63 圖4-5 基礎位於坡肩時受α、β作用下之破壞面示意圖.......... 45 圖4-6(b) 載重傾斜角修正係數ηi 與β/φ之關係圖和迴歸公式比較62 圖4-6(b) 參數m 與φ 之關係圖和迴歸公式................... 63 圖4-7(a) 水平慣性力修正係數ηe 與kh 關係圖和迴歸公式(φ =30°)................................................... 64 圖4-7(b) 水平慣性力修正係數ηe 與kh 關係圖和迴歸公式(φ =35°) .. ................................................64 圖4-7(c) 水平慣性力修正係數ηe 與kh 關係圖和迴歸公式(φ=40°) .................................................. 65 圖4-8(a) 斜率Se 與坡角α關係圖和迴歸公式................. 65 圖4-8(b) 參數S1 與φ 之關係圖和迴歸公式.................. 66 圖4-9 基礎受水平地震力作用示意圖........................ 66 圖4-10 基礎位於坡肩時受α、β、kh 作用下之破壞面示意圖.... 50 圖4-11(a) 平地基礎地震時Nγ 比較(φ =30°) ................ 67 圖4-11(b) 平地基礎地震時Nγ 比較(φ =40°) ................ 68 圖4-12(a) 坡肩基礎地震時Nγ 比較(φ =30°);(Kumar & Mohan Rao,2003)............................................... 69 圖4-12(b) 坡肩基礎地震時Nγ比較(φ =40°);(Kumar & Mohan Rao,2003)............................................... 70 圖4-13(a) 比較ηie 分析值和ηie = ηi.ηe (φ =30°) ........ 71 圖4-13(b) 比較ηie 分析值和ηie = ηi.ηe (φ =35°)......... 71 圖4-13(c) 比較ηie 分析值和ηie = ηi.ηe (φ =40°) ........ 72 圖4-14(a) 比較ηie 分析值和ηie 迴歸值 (φ =30°)............72 圖4-14(b) 比較ηie 分析值和ηie 迴歸值 (φ =35°)............73 圖4-14(c) 比較ηie 分析值和ηie 迴歸值 (φ =40°)........... 73 圖4-15 參數t 與α 之關係圖和迴歸公式..................... 74 圖4-16(a) 本研究中各條件下ηs、ηi、ηe 經驗公式結合之準確性表示圖.....................................................75 圖4-16(b) 本研究中各條件下ηs、ηie 經驗公式結合之準確性表示圖...................................................... 76 圖4-17(a) 經驗公式計算Nγ 和分析值之比較 (φ =30°) ....... 77 圖4-17(b) 經驗公式計算Nγ 和分析值之比較 (φ =40°) ....... 78 圖5-7 將基礎後退承載力以坡肩基礎、和覆土影響表示......... 83 圖5-1 基礎後退位置與破壞面示意圖......................... 86 圖5-2(a) 坡頂基礎之Nγ 與b/B 關係圖 (φ =30°) ............ 86 圖5-2(b) 坡頂基礎之Nγ 與b/B 關係圖 (φ =35°) ............ 87 圖5-2(c) 坡頂基礎之Nγ 與b/B 關係圖 (φ =40°) ............ 87 圖5-2(d) 坡頂基礎之Nγ 與b/B 關係圖 (φ =45°) ............ 88 圖5-3(a) 坡頂基礎之Nγ 與b/B 關係圖;比較於Graham (1988) 88 圖5-3(b) 坡頂基礎之Nγ 與b/B 關係圖;比較於Meyerhof (1957) ...................................................89 圖5-4(a) 不同α下之後退修正係數ηb 與b/B 關係圖 (φ =30°).. 90 圖5-4(b) 不同α下之後退修正係數ηb 與b/B 關係圖 (φ =35°).. 90 圖5-4(c) 不同α下之後退修正係數ηb 與b/B 關係圖 (φ =40°).. 91 圖5-4(d) 不同α下之後退修正係數ηb 與b/B 關係圖 (φ =45°).. 91 圖5-5 (b/B)t 與φ之關係圖................................ 92 圖5-6(a) Sb 和α之關係圖................................. 92 圖5-6(b) x 和φ 之關係圖................................. 93 圖5-6(c) z 和φ 之關係圖................................. 93 圖5-8(a) 直接解之ηb 比較................................ 94 圖5-8(b) 間接解之ηb 比較................................ 94

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