砂土中模型樁之減振與摩擦特性

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Title:	砂土中模型樁之減振與摩擦特性
Authors:	張永欣;Chang,Yung-hsin
Contributors:	土木工程學系
Keywords:	模型樁;減振器;摩擦樁;加速度;永久沉陷量;model pile;vibration damper;friction pile;acceleration;permanent settlement
Date:	2014-07-29
Issue Date:	2014-10-15 14:29:50 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究以消能為出發點，進行一系列的模型樁摩擦試驗，提出一種改良基樁的方式，藉由減振器的功能，降低受衝擊的基樁和樁周土壤之振動及永久性沉陷。如摩擦樁下方無承載層，其支承力幾乎全由樁身摩擦力所提供，當受到之衝擊力大於樁身摩擦阻抗時，便會產生永久性沉陷。本研究以摩擦樁為研究對象，探討加裝減振器後，其振動與沉陷量的減少情況。試驗採用一圓筒狀鋼製土槽，中央架設模型樁，下方套有一空心套管，使模型樁無任何點承力支撐，並以峴港砂土試體模擬現地情況，將落錘以四種落距對模型樁進行衝擊加載，以加速度計量測模型樁周遭土壤各深度的最大加速度，並以LVDT量測減振器的動態變位量及模型樁的永久沉陷量，最後透過數據比較未改良模型樁與改良模型樁之差異。由試驗結果可以得知，加裝液壓減振器，確實能吸收振動能量，降低樁身永久沉陷量，但也因此使得摩擦消能之作用未完全發揮，故產生液壓減振改良模型樁之樁周土壤加速度仍略大於未改良模型樁之情況。;This study set a vibration damper on pile head to reduce shock vibration and permanent settlement of model pile caused by impact loading. If there is no bearing stratum under the tip of pile, the bearing capacity of pile will be completely supported by shaft friction. When the impact force is greater than the frictional resistance of pile foundation, some permanent settlement will be caused. This study chose the friction pile as the research object, and investigated its situation of vibration and settlement reduction with vibration damper. The test used a hollow tube under the model pile to remove the bearing capacity of model pile. Danang sand was used to fabricate test specimens. The drop hammer was used to impact the model pile with some different drop heights. Accelerometers and LVDT were used to measure the data of acceleration, dynamic displacement of vibration damper and permanent settlement of model pile. According to the test results, the vibration of the model pile with hydraulic damper is larger than the untreated one, but the target of reducing permanent settlement of model pile is achieved. From the viewpoint of energy, the vibration damper absorbed the impact energy indeed and reduced the permanent settlement of model pile.
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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