土石流為嚴重自然災害，為了解土石流在河道中的影響，本研究以PFC3D數值模式進行顆粒流在渠道中受不同固床工位置之影響。討論三種不同顆粒數量(堆積高度(H)為10cm、7.1cm、5cm)，每種數量放置至少八個不同位置之等高障礙物(h)。比較各種組合的結果，並藉由實驗來驗證模擬的結果是否精確。不同閘門抽離方式會對顆粒流初始破壞造成影響，分為主動破壞和被動破壞。顆粒流靜止時的表面坡度會隨著障礙物與閘門距離的增加，先由一初始坡度降低後再提高，而不同堆積高度與障礙物高度關係也會影響到顆粒靜止時的坡度。改變堆積高度與障礙物高度比(H/h)時，隨著障礙物距離的增加，較高H/h的阻擋率變化會較明顯，較低H/h的阻擋率變化則較小，而不動顆粒則在高H/h時變化較小，低H/h時變化較明顯。

Landslides debris flows are serious natural disasters. In order to understand the influence of ground sills on the granular flow in the channel, this is employs PFC3D numerical model to simulate the particle flow in the channel by different groundsill positions. We have three different particle quantities(Stacking height(H)：10cm、7.1cm、5cm) and 8 locations at the same obstacle height. The numerical results of the various combinations are close to the results obtained from flume. Different gate extraction methods affect the initial failure modes of the particle piles, which is divided into active failure and passive failure. After the release of the particle pile, its surface slope increases as the distance between the obstacle and the gate increases first and declines later. The relationship between the stacking height and the obstacle height also affects the final surface slope. When increasing the ratio of stacking height to obstacle height (H/h), the blocking rate will decrease and the trend is sensitive to the distance to the obstacle. The portion of immobile particles on the upstream channel bed is more pronounced at low H/h values.

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