應用FLO-2D於臺灣中部地區土石流流況分析之研究

Debris Flow Simulation of Central Taiwan Area Using FLO-2D

彭繼賢(Chi-Hsien Peng)

指導教授 ： 林美聆

國立臺灣大學/工學院/土木工程學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.01055

摘要

臺灣位於板塊的交接帶，屬於年輕不穩定地質，地質破碎常造成集水區土石成為土石流的料源，每逢夏季颱風侵台時，崩坍土石往往順流而下，造成下游地區災害頻傳。如民國85年的賀伯颱風，90年的桃芝颱風，93年的敏督利颱風，都造成臺灣生命財產的重大損失。本研究冀望能利用FLO-2D數值軟體建立一套完整而合理的分析模式，配合流槽試驗，針對參數加以探討，找出合理參數，並將參數帶入現地，探討流動狀況與堆積狀況，以決定土石流的潛勢區域，期望對於人民生命財產之維護有所助益。
本研究引入謝正倫、蔡元芳(1998)所做的流槽試驗，建置等比例放大模型以進行FLO-2D的數值模擬。在參數敏感度分析後，發現流變參數中的賓漢降伏應力與賓漢黏滯係數分別對於堆積狀態與流動狀態有很大的影響，因此利用兩位學者對於土石流扇狀地的堆積幾何特性研究成果，來修正賓漢降伏應力；再配合各地流速監測資料，來修正賓漢黏滯係數，進而推求應用於現地的合理參數組合。
在現地案例分析方面，採用在賀伯颱風(民國85年)發生土石流災害的陳有蘭溪流域及在桃芝颱風(民國90年)發生土石流災害的豐山地區以及部份陳有蘭溪之子集水區(二廍、三廍、豐丘)為研究區域，蒐集相關之地形、雨量資料後，利用修正後之參數進行現地案例之數值模擬，再配合災後的航空照片、微地形進行判釋，以及前人的探勘報告，與模擬結果所得之土石流影響範圍、堆積土方量及河道流速進行差異比對，並對各案例模擬結果之適用性進行討論。從結果來說，對於影響範圍與河道流速而言，模擬的結果相當良好，而堆積土方量則因不同區域，有不同的差異量。以上述之結果，期望能對於土石流潛勢區域的判定，工程設施之復健與規劃，土石流避難疏散路線規劃，能有所貢獻。

關鍵字

土石流 ； 數值模擬 ； 流變參數 ； FLO-2D ； 陳有蘭溪 ； 豐山地區

並列摘要

Taiwan is on the juction of tectonic plates, and is a young, unstable geological area. Fractural stratums contribute to the sources of debris in the basin. Typhoon often induce debris flow hazard, many disasters occurred in the downstream reaches causing damages to people’s life and property, such as typhoon Herb (1996), typhoon Toraji (2001), typhoon Mindulle (2004). In this research, processes of numerical simulation related for debris flow routing is formulated using software FLO-2D, and parameters discussed. The calibrated parameters are then used in in-situ simulation and flow and deposit conditions are discussed. The results can provide information for hazard zoning and helps to provide assistance in people’s life and property.
In this research, results from laboratory experiments by Shieh and Tsai (1998) are used. A debris flow model of the test has constructed using FLO-2D, which is a dynamic flooding routing simulation model. After parameter studying, it was found that both Bingham yielding stress and Bingham viscosity of rheological parameters affected deposit and flow condition. The Bingham yielding stress were determined using deposition evolution of debris-flow fans by Shieh and Tsai; while the Bingham viscosity was determined using monitored velocity data. The rational combinations of parameters are proposed for the case studies.
Case studies in this research consist of several phases. First, data of debris flow cases such as topography and rainfall information from Chenyulan river basin during typhoon Herb, typhoon Toraji, and Fong-Shan during typhoon Toraji are compiled. Second, numerical simulation was performed using FLO-2D, results were presented as deposit area, maximum velocity, and debris volume. Simulation results are compared with aerial photos, microgeomorphology study and velocity estimated by previous researchers. And then, suitable conditions for using this model and suggestions for future research are proposed. The proposed method appears to be helpful to deciding hazard zone, judgement of emgineering, planning of evacuation and shelter.

並列關鍵字

Debris Flow ； Numerical Simulation ； Rheological Parameters ； FLO-2D ； Chenyulan river ； Fong-Shan

參考文獻

謝正倫、江志浩、陳禮仁 (1992)，「花東兩縣土石流現場調查與分析」，中華水土保持學報，第23卷，第2期，第109-122頁。

Arattano, M. (1999), “Monitoring the propagation of a debris flow along a torrenty’’, Hydrological Sciences Journal, Vol. 44, No. 5, 1999, pp.811-823.

Bagnold, R.A. (1954), “Experiments on a gravity-free dispersion of large solid spheres in a Newtonian fluid under shear”, Proceeding Royal Society of London, series A, No. 225, pp. 49-63.

Berti, M., Genevois, R., Tecca, P.R., (1999), “Field observations of a debris flow event in the Dolomites”, Geomophology, Vol. 29, pp. 265-274.

Bovis, M.J. and Jakob, M. (1999), “The role of debris supply conditions in predicting debris flow activity”, Earth Surface Processes and Landforms, Vol. 24, pp. 1039-1054.