Numerical Simulation of Debris Flow and the Characteristic of Rheological Parameters

台灣地區土石災害頻繁，地震頻繁造成地質破碎，使崩塌於溪流源頭及上游之土石成為土石流料源，在颱風或豪雨的侵襲之後，將崩塌土石與水混合流出，造成多處土石災害。有鑒於此，近年來有釵h的學者專家投身於土石流的相關研究，希望能更瞭解土石流的發生機制、流動過程及其淤積結果，以減少土石流災害所造成的衝擊及損失。而本研究擬建立一套合理的土石流災害範圍及規模數值模擬參數及方法流程，以期對防災計畫的擬定有所幫助。 在前人對於土石流數值模擬的研究中，流變參數為一具有爭議性的參數，室內實驗往往因為取樣的困難及土石流發生當時體積濃度的不確定而使實驗所得流變參數與土石流發生時的流變參數有著極大的差異。本研究引入謝正倫、蔡元芳(1998，1999)所做的流槽試驗以及對於土石流扇狀地的堆積幾何特性研究成果，建置等比例放大模型進行Flo-2D的數值模擬，並進行相關參數的敏感度分析，以及特性的探討，並引入判定係數討論各參數之合理性，進而推求應用於現地的合理參數組合。 在現地案例的分析部分，選定在賀伯颱風(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為研究區域，蒐集相關之地形、雨量資料，並建立各流域土石流影響因子之溪流資料庫。最後以本研究所建立之模式進行現地案例之數值模擬，並利用災後的航空照片、微地形進行判釋，與模擬結果所得之土石流影響範圍、最大堆積深度及堆積土方量進行差異比對，並對各案例模擬結果之適用性進行討論。最後並提出此模式的適用情形及改進建議，以供日後相關研究參考。Debris flow is a very serious disaster which always leads to huge damages in Taiwan. Fractural stratums and provide landslide caused by frequent earthquakes are the sources of debris. After typhoon or downpour, debris and water mixes to form debris flow. A lot of efforts have been done in recent years to understand the triggering criteria, flow routing and deposition of debris flow in order to reduce the impact and losses caused by debris flow. In this research, parameters needed and processes for a numerical simulation method for debris flow routing and deposition is formulated to provide reference for hazard zone mapping. In previous studies of numerical simulation of debris flow, rheological parameters are ontroversial. Because of the difficulty of sampling and uncertainty of sediment concentration during debris flow, rheological parameters obtained from laboratory testing are significantly different from those observed in field. In this research, results from laboratory experiments and deposition evolution of debris-flow fans by Shieh and Tsai(1998,1999) are used. A debris flow model of the test constructed using Flo-2D, which is a dynamic flooding routing simulation model. Parametric studies and characteristics analyses are also performed. The rationality of parameters is discussed and the reasonable combinations of parameters are proposed for the case. Case studies in this research consist of three phases. For the first phase, data of debris flow cases such as topography and rainfall information from Chenyulan river basin during 1996 typhoon Herb and Fong-Shan during 2001 typhoon Toraji are compiled and used to establish a debris flow influence factors database. For the second phase, numerical simulation was performed using Flo-2D, results were presented as area, maximum depositing depth, and volume deposited. Simulation results are compared with aerial photos and microgeomorphology study. Finally, suitable conditions for using this model and suggestions for future research are discussed.第一章 緒論 1 第二章 文獻回顧 5 第三