在臺灣形成造山運動時,形成地形陡峭且地質破碎的地理環境。除此之外,臺灣也位於西太平洋颱風路徑上,颱風季節所帶來的強風豪雨,使原本就陡峭、破碎的地表土壤沖刷流失、山坡地崩塌,造成慘重之災情,其中以土石流災害為甚,所以,本研究藉由PFC3D模擬水槽試驗所獲得的結果可供作為防範土石流災害的參考。 目前土石流的模擬及研究上大多數是以室內水槽試驗進行對現地土石流情況的模擬,或是以分離元素法PFC2D探討土石流體內顆粒之運動機制。因此,本研究利用PFC3D模擬土石流室內水槽試驗並與楊子阜(2005)之試驗結果做比較,首先依照粒徑分布等實驗數據進行參數分析 ; 接下來模擬不同壩體型式對土石流堆積特性之影響,藉由數值程式模擬室內水槽之攔阻試驗將模擬所得之堆積深度、堆積長度的探討來加強室內試驗與現地的關聯性,提供數值模擬驗證室內水槽試驗的一種依據,希望藉由本研究提供有利之佐證。 綜合各項結果可知,在無攔阻試驗中當土體微觀摩擦角越大時,土體滑動速度越慢 ; 坡面摩擦角越大時,啟動土石滑動所需之摩擦角越小,且堆積範圍隨著微觀摩擦角增加而縮小 ; 在模擬梳子壩及重力壩之攔阻結果中與室內水槽攔阻試驗之堆積深度及範圍相當接近。
Most of the modeling and studies of debris flow have been used water flume experiments in a laboratory or used distinct element method based software, PFC2D, to investigate the kinematics inside the particles of debris flow. Therefore, the study uses PFC3D to model and compare the results of water flume experiments by Yang (2005). Parameter studies were carried on according to the grain-size distribution used for the experiments.The impacts of different blocking and retaining structures on the characteristics of deposition depth and form are modeled. In order to demonstrate the applicability using numerical modeling for debris flow, the deposition depths and ranges obtained from water flume tests and numerical experiments are evaluated and compared. For numerical experiments without retaining system, debris flow moves faster as the friction angle between particles becomes smaller under the same inclined slope angle of 19 degrees. For modeling debris flow with blocking or retaining system or dam, the results of the deposition length and accumulated depth in front of the dam are similar to the findings by Yang (2005) for concrete slit dam and gravity dam.