| 摘要: | 動力夯實工法於1993年引進到台灣，並成功地應用於土木工程界之土壤改良作業。然而，至今尚未發展出完整之有效影響深度推估模式。基此，本研究探討動力夯實工法有效影響深度之推估模式。此外，由於近年環保意識高漲，施工造成之鄰損事件與日俱增，如何有效防止或降低施工所引致之波動，為一重要課題。因此，本研究進行一系列之室內縮尺砂土模型夯擊試驗及台中港區水力回填廠區之現地量測，以剖析波動阻隔。 本研究利用圓桶形土槽模擬夯擊試驗，探討動力夯實工法施工有效之影響深度，試驗時改變多項夯擊條件，得到夯擊中心之夯擊應力隨深度變化之關係式。此一關係式配合夯擊荷載之推估公式，可評估夯擊之有效影響深度。經與麥寮六輕土壤改良實際案例之現地試驗結果比較後，得知此評估方式在考量現場與室內試驗土層差異之相關修正後，可得到一良好之預估結果。 此外，由動力夯實施工引致之波傳阻隔試驗結果得知，夯擊瞬間所測得土層表面不同水平距離處之振幅，因幾何與材料阻尼效應，使其隨距離之增加而迅速衰減。將夯擊能量加入振幅衰減公式中可獲得一個合理之經驗公式，利用此經驗公式配合前人發展出之判斷準則，即可評估所選取之夯擊能量在施工時是否會對鄰房造成損傷。 隔振設施之阻隔效果研究試驗結果得知，對於被動阻隔所探討的振源與隔振溝間之距離，理論上是愈遠愈好，但若受限於施工地區的大小時，則最少須大於3倍的振波波長。在主動阻隔方面，經不同深度之隔振溝的試驗可知，若欲使隔振溝設置後，能降低地表加速度振幅至無隔振溝存在時的0.25倍，則其深度至少須為0.7倍的振波波長，但當隔振溝深度大於0.9倍的振波波長時，隔振效果已無明顯的增加。 Dynamic compaction method was introduced to Taiwan in 1993, and has been applied to soil improvement operation in civil engineering successfully. However, the models of prediction effective influence depth had not been developed completely. Thus, the purpose of this research was to study the effective influence depth prediction model of dynamic compaction method. Besides, due to the high tension of environmental consciousness, and the currently increasing events of adjacent building damage caused by constructional operation, how to effectively prevent or reduce wave propagation caused by site operation would be an important issue. Therefore, in this study a series of small-scale compaction model tests and in-site exam on hydraulic-filled reclaimed land at Taichung harbor were carried out in order to elucidate the isolation of wave propagation. In this study, dynamic compaction model tests in circular chamber were conducted to investigate the effective influence depth of sandy soil improved by dynamic compaction method. By changing the conditions of compaction, the formula related to the center of impact stress and depth was obtained. This formula coupled with the formula of impact load could predict the effective influence depth. In comparison with the experimental results of the Sixth Oil Refinery ground modification at Mai-liao, the prediction method had obtained good results after related modifications in taking into account of the differences of soil layer conditions between in-situ and lab tests. Besides, according to the results of isolation of wave propagation tests, the amplitude measured from different horizontal distances on the ground surface at the moment of impact decayed quickly with the increase of the horizontal distance due to the geometrical and material damping effect. By adding the impact energy to the equation of wave decay, a reasonable experimental formula was obtained. Using this formula and the judgment guideline proposed by predecessor, the influences of impact energy on the adjacent building could be evaluated. Results from the study of effective isolation equipments showed that in the aspect of passive isolation, the farther the distance between the impact source and the isolation trench the better the isolation effect theoretically. However, if the size of operation area was restricted, the distance should be at least 3 times greater than that of the wavelength. In the aspect of active isolation, the results of different depth of isolation trench tests indicated that with the installation of isolation trench, if one wanted to reduce the accelerated amplitude of ground surface to 0.25 times of that without isolation trench, the depth of isolation trench should be at least 0.7?R. However, when the depth of isolation trench was greater than 0.9?R, there was no significant increase in the effect of isolation. |
