The Characteristics of Debris-Flow on The Different Discharge

Abstract

土石流的形成需具備大量土砂堆積物、一定範圍的坡度變化、水量的 供給等三個必要因素。因此本研究利用渠槽試驗以三種不同粒徑級配、六 種渠床坡度變化、八種不同上游水量供給之條件，來模擬土石流之形成、 流動等過程，藉以推估上游流量的供給與土石流性狀之相互關係，希冀研 究之成果能與現場資料結合，作為土石流危險區判別之依據。 試驗結 果顯示:1.渠槽模擬試驗結果可以利用段波高度、泥砂體積濃度、渠床坡 降等 三個參數因子，對是否形成土石流作有效的判定。2.上游流量 越大，土石流所挾帶的粗顆粒比例越高，原土石堆積床面 將有細粒化的 現象產生。3.上游流量供給的多寡，確實對土石流之泥砂體積濃度、段波 高度、 流速及輸砂量等有顯著的影響。由此可知，集水區流量因子可 做為土石流危險度判別的重要參考依據。

The debris-flow takes shapes by the great amount of sands ,the variant of slopes , and the supply of flux . The laboratoryexperiments try to simulate the debris-flow's shape and fluid by three kinds of gravel distribution , six kinds of slopes andeight kinds of flux . According to the relationship between upstream inflow and debris-flow , we hope that this study contribute to divide the risk area . The results of the experiment are as following:1.In the laboratory experiments , it is able to distinguish the characteristic of debris-flow with the relationship of those parameters , the depth of debris-flow , the sediment concentration and the bed slope .2.The more the runoff is , the more amount of the rough gravel will carry from the up stream . The rate of the exiguous gravel on the up stream will become on the increase .3.How much the flux is , it will affect the sediment concentration of debris-flow , the depth of debris-flow and the velocity of debris-flow . It can compartmentalize the risk area with the reason of the runoff .