動力壓密工法施工引致地表振動之阻隔

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Title:	動力壓密工法施工引致地表振動之阻隔
Authors:	李嶸泰;Ro-Ti Lee
Contributors:	土木工程研究所
Keywords:	動力壓密工法;主動阻隔;被動阻隔;隔振溝深度;隔振溝與振源之距離;dynamic consolidation method;active isolation;passive isolation;depth of isolation trench;distance between isolation trench and source of im
Date:	2000-07-07
Issue Date:	2009-09-18 17:06:01 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本研究係於試驗室中，以縮尺砂土模型進行模擬夯擊試驗。主要探討動力壓密工法施工時，產生之地表振動的有效阻隔方法。試驗分為兩個部份，一為主動阻隔，即是欲找到一有效阻隔波傳的隔振溝深度；另一為被動阻隔，即探討隔振溝與振源之間的距離對於阻隔表面波傳遞的效果之影響。由試驗結果得知，夯擊瞬間所測得土層表面不同水平距離處之加速度振幅，因幾何阻尼效應及材料阻尼效應，使其隨距離之增加而衰減。所以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，此與Segol(1978)利用數值模擬所得之結果相同。另外，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。 This research was carried out by simulated dynamic compaction test with small-scale sandy ground model in laboratory. The main purpose was to study the effective isolation method of ground vibration generated by operation of dynamic consolidation method. The experiment was divided into two parts, one is the active isolation, i.e., to find the depth of isolation trench for effective isolation of wave transmission; the other one is the passive isolation, i.e., to study the effect of distance between isolation trench and source of impact to the efficiency of isolation of surface wave transmission. From the results of experiment, it was revealed that the amplitude of ground surface acceleration of different horizontal distances measured at the moment of impact were reduced as the distance increased due to the geometrical and the material damping effect. Therefore, as to the distance between the impact source and the isolation trench in the concern of passive isolation it was found that the farther the distance the better the isolation effect, theoretically. However, if the size of operation area was restricted, the distance should be at least greater than 3 times of wavelength. This result was consistent with that of Segol’s study (1978) using digital simulation. Besides, in the studies of active isolation, the experimental results from different depth of isolation trench indicated that the depth of isolation trench should be at least 0.7 times of wavelength to reduce the amplitude of ground surface acceleration to 25 percent of that without an isolation trench. However, when the depth of isolation trench was greater than 0.9 times of wavelength, there was no significant increase in the effect of isolation.
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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