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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/68399


    Title: 花崗岩單軸壓縮破壞試驗之電場信號變化研究;Electric signals of granite failure under uniaxial compression
    Authors: 廖婉如;Liao,Wan-Ru
    Contributors: 地球科學學系
    Keywords: 電場;震前信號;單軸壓縮試驗;electric signals;earthquake precursor;uniaxial compression experiments
    Date: 2015-08-31
    Issue Date: 2015-09-23 11:31:15 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 為了減少地震所造成的災害損失,科學界不斷研究地震的震源機制與伴隨而來的自然現象,試圖建立可靠的地震預警系統應用在生活上。被視為地震前兆的現象中許多與電磁場有關,地電場的異常變化是其中一種,這是由於地殼中石英礦含量豐富,並且石英具有將應力轉為電能之壓電性質,故有研究以壓電效應解釋其成因。地震發生時,地殼不斷受到擠壓,當累積應力超過負荷範圍導致其破裂形成斷層。而單軸壓縮試驗的試驗過程中,岩石垂直方向體積持續被壓縮,所加壓力超過其單壓強度時岩石被破壞。因為上述兩種過程十分相似,以此推論在岩石被破壞前,電場會出現可以視為破裂前兆的異常行為。
      地震機制相當複雜,前兆現象也並非每個地震事件都有,具有異常現象之地電場資料可遇不可求。但是單軸壓縮試驗可以快速增加資料數量,實驗室環境也相對自然界單純,能更有效率地研究破裂前兆的成因。本研究使用單軸壓縮試驗模擬地震事件中斷層的產生,地殼則是以礦物組成石英佔相當比例的花崗岩代替,藉由在花崗岩表面製作數個銀質電極,量測岩石各區域之表面電場於加壓過程中的變化,期望在岩石破壞前出現異常行為。為了研究電場在頻率域的變化,將處理後之電場資料做強化型Morlet轉換進行時頻分析。研究結果顯示在岩石被破壞前,86筆電場時間序列中有32筆出現異常抬升或下降;時頻域則是有7支試體於低頻帶出現大量信號,部份通道其信號強度甚至與花崗岩崩毀時相當,本研究認為上述兩種現象為花崗岩之破裂前兆。
    ;Abnormal changing of the electromagnetic field is regarded as one of precursor for earthquake. The stress keeps loading crust before earthquake happens, the rock failure processes of earthquake is similar to uniaxial compression experiment.
    This study reports the relationship between electric field and rock failure during uniaxial compression. Experiments of rock samples on an electro-hydraulic servo-controlled testing machine show that the variation of electric field is closely related to rock deformation.The severe changing of the electromagnetic field during loading processes can be regarded as a precursor of unusual behavior, we expected abnormal behavior appeared before the rock broken.
    The results showed that many low frequency signals of electromagnetic field appeared before rock fracture.
    Appears in Collections:[地球物理研究所] 博碩士論文

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