https://scholars.lib.ntu.edu.tw/handle/123456789/169086
標題: | 台灣西部斷層帶附近岩體同震變形行為之研究(II) A Study on Coseismic Deformation near Fault Zone in Western Taiwan(Ⅱ) |
作者: | 林銘郎 | 公開日期: | 2003 | 出版社: | 臺北市:國立臺灣大學土木工程學系暨研究所 | 摘要: | 921 集集大地震時,由於車籠埔斷 層錯動所引發大幅地表變形與破裂, 導致變形帶上的建築物嚴重損毀及破 壞,並造成近100 公里斷層地表破裂 帶,近年來許多學者於車籠埔斷層地 表破裂沿線,以開挖槽溝的方式進行 古地震研究,因此能夠直接觀察斷層 擴展褶皺的剖面,對於研究靠近地表 褶皺構造的變形特徵與變形機制,實 為一難得的機會。本研究之分析分為 運動學模式及連續體力學數值分析二 部分,第一部份嘗試利用三角形剪切 帶運動學模式模擬斷層錯動引致之地 層變形型態,結果顯示:三角形運動 學模式可以描述自然界斷層擴展褶皺 的特徵,由集集地震後槽溝開挖剖面 之反算分析,可以了解地表下方盲斷 層的可能位態與深度,與可能的古地 震次數; 第二部分以連續體力學數值 分析結果顯示,利用連續體之力學分 析,引入界面元素以模擬斷層的存 在,可以模擬盲斷層向上擴展的過 程,為一破裂穩定發展的過程,抬升 基盤的力量需要一直增加,斷層面才 會繼續向上擴展。而所得之變形與三 角形剪切帶運動學模式所描述相似。 During the 1999 Chi-Chi earthquake, the movement of the Chelungpu fault caused large deformation of the surface of the earth, and destruction of buildings nearly along the Chelungpu fault trace. Trench excavations of the monoclinal structure were taken, and provide a good chance to study the deformation features and mechanisms of the natural monoclinal folds. This study includes two parts: the kinematic modeling and continua numerical simulation. In the first part, for the purpose of understanding the deformation of monoclinal folds induced by faulting events, the numerical modeling is done by choosing trishear kinematical model which firstly suggested by Erslev (1991). In the inverse analysis of monoclinal folds of Shijia trench profile in Nantou, the results are: (1) the ramp angle of blind fault is about 30°, and (2) the depth of fault tip now is about 7.4m beneath the hanging wall surface, and (3) there are at least two more faulting events beside Chi-Chi earthquake, and the rigid body motion of hanging wall along the fault plane are about 5, 2, 0.5 meters individually from young to old events. In the second part, in order to understanding the rationality of trishear kinematical model, the numerical simulation of the process of fault propagation is taken by running FLAC (continua numerical software) and the fault is simulated by using interface. The results are: (1) there is a triangular shear zone observed in front of the fault tip, and (2) the displacement vectors of particles rotate and decrease from hanging wall to footwall. The results are in agreement with the assumptions of trishear model. But, according to the numerical simulation, the parameters of trishear model do not keep constant in the process of fault propagation ,which should be considered when kinematical modeling is taken. Otherwise, fault propagation is a process of stable fracture propagation. If the force for basement uplift does not increase continuously, the propagation of fault plan will stop. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/2802 | 其他識別: | 912211E002048 | Rights: | 國立臺灣大學土木工程學系暨研究所 |
顯示於: | 土木工程學系 |
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912211E002048.pdf | 6.42 MB | Adobe PDF | 檢視/開啟 |
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