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碩士論文公告區 |
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| 年度： | 90 | |
| 姓名： | 歐大銓(Tai-Chuan Ou) | |
| 論文題目(中)： | 砂土中水平擴座地錨與垂直擴座地錨之錨碇行為 | |
| 論文題目(英)： | Anchorage Behavior of Horizontal Underreamed Anchors and Vertical Underreamed Anchors in Sand | |
| 摘要(中)： | ||
| 本研究乃利用SHSE模式配合FLAC3D軟體對砂土水平擴座與垂直擴座地錨進行數值分析。由數值分析發現水平地錨之拉拔力主要隨覆土深徑比H/D的增加而增加，受自由段長徑比Z/D之影響不大。雖然尖峰拉拔力、尖峰摩擦力與尖峰面承力所需位移量並不同，但是在超過臨界覆土深度Hcr後，深層地錨達尖峰拉拔力所需位移量差距幾乎一致。由於深層地錨之面承力無尖峰值，經由定義深層地錨降伏面承力Qqy所需之位移量Sq約為50%D。淺層地錨僅在Z/D＝2.5、H/D＝2.5時為摩擦力控制，其餘均受面承力所控制。由本研究亦可發現，利用「明顯尖峰面承力」之定義於水平地錨可定義出臨界深度Hcr＝8。因受剛性束制與錨碇段周圍正向應力之影響，使得水平地錨之錨碇力大於垂直地錨，本研究進一步求得其摩擦力與面承力之轉換係數F*與Q*，以設計水平地錨使用。 水平地錨之荷重傳遞曲線大致隨荷重之增加略呈等比例的方式增加。在淺層地錨時，荷重傳遞曲線略呈凹向上由錨底往錨頂傳遞之情形，在深層地錨時則有凹向下之趨勢，不過兩者之傳遞情形差異不大。淺層地錨摩擦應力之分佈較為平均，深層地錨則因面承力的逐步發揮導致應力集中於錨頂，使得錨碇段頂部之摩擦應力大於錨底而略呈梯形分佈。 |
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| 摘要(英)： | ||
| A sand model “SHSE” and a 3D numerical software “FLAC3D” have been performed to study the anchorage behavior of horizontal and vertical underreamed anchors in sand. It was found, the anchorage capacity of horizontal anchor increases with overburden depth ratio H/D, but the influence comes from free length ratio Z/D was not evident. Although the total load, shaft friction and end bearing do not reach peak values at same anchor displacement, the total load of deep anchor reaches it peak value at same displacement almost. The peak value of end bearing of deep anchor was not found, 50%D of anchor displacement can be seen when end bearing reaches yielding value. The end resistance dominates the pullout force of anchors except a shallow anchor with Z/D=2.5 and H/D=2.5. There exists a critical depth Hcr equal to 8 which differentiates the end resistance of a shallow anchor from that a anchor with deep overburden. It can been seen from results of numerical analysis, the anchorage capacity of a horizontal anchor greater than a vertical anchor due to the effect of boundary constriction and normal stress acting on fixed length. Two translated parameters F* for shaft friction and Q* for end resistance were found between the horizontal anchor from the vertical anchor. The load transfer curve increases with pullout load proportional which is concave upward transfer from bottom to top of a shallow anchor and concave downward of a deep anchor. A uniform frictional stress distribution alone fixed end was found from the shallow anchor, but frictional stress distribution along fixed end is trapezoidal for deep anchor due to stress concentrates on the top of fixed anchor end. |
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| 檔案： | 沒有相關檔案 | |
| 相關連結： | http://ethesys.lib.cyut.edu.tw/ETD-db/ETD-search-c/view_etd?URN=etd-0829102-134203 | |