樁基礎在傾斜地盤受震之數值模擬

台灣位於環太平洋地震帶(又稱環太平洋火山帶)上，每年大大小小地震不斷，根據中央氣象局的研究，台灣地區平均每年約發生18500次地震，其中有感的地震約有1000次。地震來臨時，短時間內的巨大能量會使建築物產生嚴重的損害，進而波及到生命財產安全。再者台灣的地形中，山地與丘陵等地形占大多數，此類區域的建築物在受到地震影響時可能會因為如地形效應等因素更為嚴重，因此根據內政部營建署的建築物耐震設計規範，在設計一建築物時，有許多需要考量的地方，從地形、斷層遠近到土壤性質，都是針對建築物耐震設計必要的考量。因此，本研究欲利用有限差分數值模擬軟體FLAC模擬樁基礎位在傾斜地盤受震的反應。首先利用從規範得到的該區設計譜加速度並繪出該地的設計反應譜，再根據此反應譜從Pacific Earthquake Engineering Research (PEER)的強地動資料庫得到的相似於目標反應譜的不同的地震加速度歷時，接著將這些地震歷時加載至FLAC模型，並藉由改變樁基礎長度、樁長與至基盤長度之比值等因素進行探討，將最後模擬所得之結果，從許多不同地震參數的角度進行探討，希望能找出其中的關聯性。

關鍵字

FLAC ；樁基礎；受震分析

並列摘要

Pile foundation is a very common way to support the structures built on slopes. When earthquakes strike, they may drive the slopes to move and slide, which would exert additional loading to the piles. In addition, the cyclic loading may weaken the soil surrounding the pile if the induced strain is large. All of these may cause damages to the pile foundation which, in turn, affect the structure supported by the foundation. In the discipline of geotechnical earthquake engineering, the seismic behavior of pile can be analyzed by dynamic p-y method, or dynamic finite element / finite difference analysis. In this research, finite difference analysis (using commercial software FLAC) is utilized to model the behavior of pile installed in sloping areas. Different pile lengths, ratios of bedrock depth to pile lengths and locations of piles would be considered. Moreover, effect of input ground motion variability on pile response is studied. This is achieved by using 30 input ground motions (each with different ground motion characteristics). These ground motions are selected based on the target design spectrum for Taipei Basin, which has 10-percent probability of exceedance in 50 years (corresponding to the return period of 475 years). Pile performance considered in this study includes maximum moment, maximum shear force and maximum lateral displacement. Trends of the pile response with ground motion parameters, model geometry, pile configuration and analysis types are evaluated.

並列關鍵字

FLAC ； pile foundations ； dynamic analysis ； total stress analysis ； effective stress analysis

參考文獻

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國際替代計量

樁基礎在傾斜地盤受震之數值模擬

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