複合勁度減振彈簧對砂土中模型樁動態性質之影響

曾乙哲(Yi-Zhe Tzeng)

指導教授 ： 張惠文

國立中央大學/工學院/土木工程學系/碩士(2006年)

摘要

中文摘要

交通運輸工具行經高架橋或橋樑時，可能引致振動，此振動經由橋墩傳遞至樁基，藉由基樁傳遞至承載層，再通過承載層傳遞至鄰近結構物或精密廠房之基礎，以致產生不良影響。本研究旨在探討降低此振波之較佳方法。
為降低由基樁傳遞至承載層所產生之振波對鄰近結構物或精密廠房之振動影響，且考慮避免因減振而造成減振器之動態變位量過大，故本研究於模型樁上加裝兩高度不同之彈簧改良為複合勁度減振彈簧之模型樁（簡稱改良樁），並進行一系列模型試驗。藉由模型試驗探討改良樁對於樁尖在承載層中產生振波之減振成效、未改良樁與改良樁之樁周土壤中振波波傳衰減行為、衝擊加速度和彈簧勁度與減振器最大動態變位量之關係。
由試驗結果可知，當衝擊能量大部分皆迅速以實體波形式傳遞至樁尖處，再經由樁尖為主要振源向土層傳遞能量。而未改良樁與改良樁之樁周土壤中波傳衰減行為之衰減趨勢兩者十分相似，大約隨距樁尖距離越遠而呈現衰減之趨勢。且透過減振彈簧之作用，改良樁樁尖之振波能量至少衰減至未改良樁尖振波能量之26%以下，可知複合勁度減振彈簧對於振波於樁土間傳遞具有明顯的減低效果。

關鍵字

振波 ； 變位量 ； 減振彈簧 ； 衝擊荷重

並列摘要

Abstract

Vibration caused by transportation vehicles pass through viaduct or bridge may be transmitted from piers to pile foundations. This vibration may generate waves in deep layer. The wave propagation from the bearing stratum may cause damages to the adjacent structures or high-tech production facilities. The purpose of this research was to investigate the optimum method for reducing these vibrations.
To reduce the vibration that may cause some detrimental effects to the residences, adjacent structures or high-tech production facilities, and think about avoiding large displacement of vibration suppression. So, this research designed two model piles. For one of the model piles, two springs were set on the pile head as the vibration suppression which was called the improved pile, and the other one was the original pile with no treatment. A series of model pile tests were carried out in laboratory to investigate the effects of vibration mitigation, behavior of the attenuation of wave propagation around model pile in the soil and the relationships among dynamic displacement of vibration suppression, impact energy and
From the results of experiments, it was revealed that the impact energy generated vibrations by means of pile tip and transmitted to the soil layers then generated waves. For the two kinds of model piles, the behaviors of attenuation of wave propagation approach to a similar curve and attenuate in proportion of distance. Moreover, the vibrations energy generated by the tip of the improved pile is at least decreased to 26%. It is revealed also that the wave propagation transmitted between pile and soil layers had predominant vibration mitigation.

並列關鍵字

wave ； impact ； spring of vibration suppression ； displacement

參考文獻

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