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碩士論文公告區 |
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| 年度： | 90 | |
| 姓名： | 王國鐘(Gwo-Jong Wang) | |
| 論文題目(中)： | 砂土中垂直擴座地錨之三向度分析 | |
| 論文題目(英)： | Three Dimensional Analysis for the Uplift Behavior of Underreamed Anchors in Sand | |
| 摘要(中)： | ||
| 本研究乃使用砂土SHSE模式配合FLAC3D軟體對地錨進行三向度的數值分析，並以模型試驗地錨來驗證數值分析之正確性。最後進行單支垂直擴座地錨於不同覆土深度下之各種錨碇行為之研究。經由驗證顯示本研究所撰寫之三維數值分析程式對於單支垂直擴座地錨可得到良好的模擬。 由研究結果發現，當地錨之直徑D=0.076m、長徑比L/D=4.5和相對密度Dr=70%時，地錨之拉拔力隨覆土深度的增加而增加，發揮地錨尖峰拉拔力、尖峰摩擦力與尖峰面承力所需的位移量並不一致。地錨之摩擦力具有明顯之尖峰值與殘餘值，達到殘餘摩擦力所需之位移量為40%D；淺層地錨面承力具有明顯之尖峰值，但深層地錨則無明顯之尖峰值，經由定義深層地錨發揮降伏面承力Qqy所需之位移量Sq≒25%D。 結果亦顯示本研究之淺層擴座地錨錨碇力受摩擦力控制，深層擴座地錨之錨碇力受面承力控制，其分界點Z/D約為11。由面承力係數之方式定義，地錨之臨界覆土深度大約6D，並可將地錨定義為Z/D<7.5為淺層地錨、Z/D=7.5~12為轉換地錨和Z/D>12為深層地錨。側向土壓力係數隨覆土深度之增加略為減少，尖峰摩擦力之側土壓係數Kf大約等於1.45，小於被動土壓力係數Kp；殘餘摩擦力之側土壓係數Kr則略小於靜止土壓力係數K0。地錨之荷重傳遞曲線呈凹向上之方式由錨底向錨頂傳遞，摩擦應力則大致呈梯形分佈。 |
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| 摘要(英)： | ||
| A sand model “SHSE” and a 3D numerical software “FLAC3D” have been performed to study the uplift behavior of underreamed anchors in sand, pullout test of model anchors were also carried out to verify numerical results. The uplift behavior of underreamed anchors calculated from this numerical model was in good agreement with those of model anchor tests. It was found when anchor under D=0.076m, L/D=4.5, and Dr=70% (D: diameter of anchor, L/D: fixed end ratio, Dr: relative density) conditions, the total load increases with overburden depth of underreamed anchor, but the total load, shaft friction and end resistance do not reach peak values at the same anchor displacement. The shaft friction evidenced peak and residual values, 40%D of displacement was found when shaft friction reaches residual state. The end bearing of shallow anchor shows evidently peak value, but the peak value of end bearing was not found from deep anchor, 25%D of displacement can be seen when end bearing reaches its yielding value. The mainly pullout capacity of a shallow anchor contributed from the frictional force, the end resistance dominates the pullout force of a deep anchor, the overburden depth of demarcation equal to 11D. There exists a critical depth (about 6 times of anchor diameter D) which differentiates the behavior of a deep anchor from that an anchor with shallow overburden. From the classification of end bearing coefficient, it was a shallow anchor if the overburden less than 7.5D, it would be classify to a deep anchor when overburden was more than 12D, and a transit anchor was found when overburden depth equal to 7.5D~12D. The coefficient of earth pressure decrease lightly with overburden, coefficient of earth pressure at peak friction Kf is about 1.45, and less than passive earth pressure Kp, coefficient of earth pressure at residual friction Kr is lightly less than coefficient of earth pressure at rest K0. The load curve is concave upward which transfer from bottom to top of the underreamed anchor, the frictional stress distribution along the fixed end is trapezoid. |
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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-0828102-143925 | |