2001-08-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/689200摘要：921集集地震造成台灣中部地表大幅度移位(同震變形)，地表破裂長度超過96公里，地表最大位移量將近10公尺。在斷層以西(下盤)，水平位移量朝向東南方，高程移位則呈下降。 本研究利用此區域長期GPS監測之地表變形資料及此次地震所發生的同震變形，藉由數值模擬方法，配合地質調查所得之地質背景資料，解釋台灣中部活動構造的運動模式。本研究採用有限差分連續體分析軟體FLAC (Fast Lagrangian Analysis of Continua)作分析工具，假設岩體為彈性物體，使用界面元素模擬斷層，分別進行車籠埔斷層區域之剖面及平面模擬，並且進行參數敏感度分析，以瞭解各參數對活斷層錯動之影響。 分析模式需考慮網格建立、重力平衡、初始條件、邊界條件、材料參數、界面元素及同震變形等主要分析條件。網格建立部分，剖面網格是參考Suppe(1987)建立之台灣中部構造剖面的簡化剖面，大小為30公里寬、15公里深。平面網格範圍為一長200公里、寬100公里的矩形，長軸方向與板塊擠壓碰撞方向N55W相同。 模擬結果顯示：剖面分析中，當水平應力大於垂直應力時，藉由釋放界面元素使網格自然<br> Abstract: Associated with the Chi-Chi earthquake, the surface rupture extended more than 96 km long, and there is considerable ground deformation. According to the displacement measured by GPS, to the east side of the Chelungpu fault, the average horizontal displacement is about 3~4m and oriented to the northwest direction. The largest maximum horizontal displacement reached about 8.5 m at Tungshih. The vertical displacements show uplifting and increase from south to north. On the other hand, to the west side of the Chelungpu fault, the horizontal slip direction is oriented southeast and the vertical displacement is subsiding. Besides, in the farther eastern side of the Chelungpu fault, such as Puli and Kaohsing, the vertical displacements also show descending. Based on the geological background and co-seismic ground deformation data surveyed by GPS network, this research explains the movement characterization of active structure in Western Taiwan by means of 2D numerical simulation. The rock is assumed to be elastic, and the fault is simulated by using interface. And the work is done to discuss the sensitivity of the parameter related to the faulting process. The simulation of profile shows that the phenomenon of elastic rebound is observed with fault slip when the horizontal stress is the maximum principle stress. The vertical displacement of the site in the east side, 20 km away from Chelunpu fault, shows descending, which agrees with the GPS observation. According to the simulation of horizontal deformation, the simulated horizontal displacement vectors agree with the coseismic deformation measured in site. And the region with concentration of strain energy release may guide the danger area of earthquakes.集集地震FLAC同震變形數值模擬Chi-Chi earthquakeFLAC,coseismic deformationnumerical modeling