平移斷層周圍地表震間變形行為之研究

The Study of Interseismic Ground Deformation near Strike-slip Faults

張增糴(Tseng-Ti Chang)

指導教授 ： 鄭富書

國立臺灣大學/工學院/土木工程學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.00580

摘要

台灣位於環太平洋地震帶，是典型的板塊碰撞所產生之大陸邊緣島嶼。由於菲律賓海板塊六百萬年以來，不斷的擠壓歐亞板塊，台灣島遂得以誕生並成長，造山運動迄今仍在激烈的進行，引發台灣旺盛的地震活動，同時地層之變形亦極為強烈，造成諸多之褶皺與斷層，充斥台灣本島。斷層在地殼材料中可視為一連續體中的破裂面，理論上有關破裂面受力在其造成的變形，已有相當的研究，但是在相關理論應用在斷層仍相當缺乏。本研究擬利用此一方面的理論在斷層附近的地表變形，推估其發生錯移時產生的地表位移量。本研究藉由物理模型試驗觀察平移斷層發生延展 ( propagation ) 前因受應變能量累積導致周圍地表變形的過程，並以數值模擬加以驗證，使吾人能有機會對平移斷層震間運動機制有更深入的探討。
本研究物理模型中，選用果凍作為模擬材料，其材料變形特性為線彈性、可承受較大的應變能，符合本研究欲觀測裂縫延展 ( propagation ) 前變形行為之目的。此外，於物理模型中，以3維PIV分析其變形過程，進一步得到裂縫周圍表面鉛直向位移大小。於數值模型中，採用有限元素分析軟體 ABAQUS做分析並驗證物理模型的正確性，希望能夠更進一步掌握平移斷層延展前地表變形行為。

關鍵字

平移斷層 ； 物理模型 ； 數值模擬 ； 震間變形 ； 立體視覺質點影像速度儀

並列摘要

Taiwan is located in the circum-pacific seismic zone, which is a typical convergence plate. Due to the convergence mechanism, there are many folds and faults in Taiwan. The discontinous nature of faults allows them to be trated as large cracks in brittle material. Thus, linear elastic fracture mechanics can be applied to evaluate the stresses and the associated ground surface displacement resulting from fault movement. This research simulated the ground surface deformation before the strike-slip faults propagated via physical model and verified by the numerical analysis.

The material of physical model in this research is jelly, which property is linear elastic and able to accept the large deformation. It accorded with the purpose of simulating the deforamtion before cracks propagated. Moreover, to better understand this deformation process, we monitor the displacement field in scaled tectonic model experiments using high-resolution optical image correlation techniques ( stereoscopic particle imaging velocimetry, SPIV ) .After the processing of Stero PIV, it generated the vertical ground surface displacement near crack. In the numerical model, we adopted the finite element method (ABAQUS) to verify the results of physical model.

In this research, we considered three mode of strike-slip faults that influence the ground deformation near faults, such as fault mode, blind fault mode and multiple faults mode. In the fault mode, we considered the influence of dip angle; In the blind fault mode, we consider the depth of overburden; In the multiple faults mode, we considered the geometry of two cracks.

並列關鍵字

Strike-slip faults ； Physical model ； Numerical analysis ； Interseismic deformation ； Stereoscopic particle image velocimetry

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