河床中細微士砂對輸砂現象之影響

The Influence of Fine Sediment of River Bed on Sediment Transportation

黃千輔(Chian-Fu Huang) ； 蔡元融(Yuan-Jung Tsai) ； 汪楷竣(Kai-Chun Wang) ； 謝正倫(Chjeng-Lun Shieh)

《中華防災學刊》 4卷1期 (2012/02) Pp. 31-39

https://doi.org/10.30052/JTDPS.201202.0004

摘要

台灣頻繁的地震與颱風事件，是造成大量崩塌的主因，不但降低了土石流的發生門檻，而且對於一般河道的輸砂現象也有明顯的改變，由Egashira（1997）的理論，細微土砂在這個現象中有重要的影響，本文利用室內動床實驗以不同比例的細微土砂對於河道輸砂現象的影響。本文實驗共分自然鋪床與人工鋪床兩種，實驗用砂包含粗砂及細砂兩種，實驗觀測項目包含輸砂現象與輸砂量量測，從成果得知，在不同比例的泥砂組成對於河道輸砂之影響，逕流密度的增加不但會降低土石流的發生門檻，更會提升原有河床之輸砂量，此現象會在細砂比例超過某一比例後達到穩定。

關鍵字

細微土砂 ； 輸砂量 ； 土石流發生條件

並列摘要

In Taiwan, the catastrophic typhoon and earthquake are both factors to trigger serious landslides in mountains. The landslides not only decreased the debris flow occurrence condition, also increased the sediment transportation. According to Egashira's theory (1997), fine sediment plays an important role with this phenomenon. In this paper, a move-bed experiment is set to discuss the variation of sediment transportation with different content of fine sediment.There are two setting of move-bed, natural deposition and artificial deposition, with mixture coarse and fine sediment. The data record in the experiment is the depth of sediment transport layer and sediment transport rate. With the result, the increasing of fine sediment decreased the debris flow occurrence condition. The sediment transport rate (coarse sand) is increasing with the increasing of fine sediment. This increasing would reach a threshold with specific ratio of fine sediment.

並列關鍵字

fine sediment ； sediment discharge ； debris flow occurrence condition