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。本研究旨在探討上述振波之傳遞及降低此振波的方法。 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，本研究於基樁上加裝彈簧改良為減振基樁，並進行模型試驗。藉由模型試驗探討減振基樁對於樁尖在承載層中產生振波之減振成效、原模型基樁與減振基樁之樁周土壤中振波波傳衰減行為、衝擊能量和彈簧勁度與減振基樁垂直位移之關係。 由試驗結果可知，當衝擊能量藉由基樁傳遞到承載層所產生之振波，傳遞到承載層與砂土層之界面時，振波大部分能量會沿著界面傳遞出去。原模型基樁與減振基樁之樁周土壤中波傳衰減行為之衰減趨勢兩者非常相似，大約隨距離呈比例性的衰減消散。當勁度比小於1.6時，減振基樁樁尖所產生之振波能量比原模型基樁樁尖所產生之振波能量減少50%以上，可知減振基樁對於振波於承載層與承載層界面之傳遞有明顯的減低效果。 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 is to investigate the wave propagation in soil layers and the 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, this research designed two model piles. One of the model piles, a spring is set on the pile head as the vibration suppression, and the other one is 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 vertical displacement of model pile, 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 bearing stratum then generated waves. If the waves transmitted to the interface layer between the bearing stratum and the loose sand stratum, parts of energy would be transmitted outward by the interface layer. 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. For the stiffness ratio lower than 1.6, the vibration energy generated by the pile tip of vibration suppression is decreased to 50% of that generated by the original model pile. It is revealed also that the wave propagation transmitted by bearing stratum and the interface layer had predominant vibration mitigation.
