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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/71125

    Title: 不同水砂比及渠道坡度對沖積扇型態之影響
    Authors: 陳瑞遠;Chen,Rui-Yuan
    Contributors: 土木工程學系
    Keywords: 沖積扇;渠道坡度;積水深度;堆積角度;Alluvial fan;Channel slope;Base level;Foreset, Topset
    Date: 2016-07-22
    Issue Date: 2016-10-13 12:07:47 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 台灣地震頻繁,土層淺薄且鬆軟,加上近年全球氣候急遽變化,高強度降雨事件增加,使得山崩、岩屑滑移與土石流事件發生頻率極高。台灣地狹人稠,山麓沖積扇成為許多村莊、公路的聚集地及必經之路。若土石流災害發生時,將對村莊、公路造成嚴重的損失。本實驗使用顆粒為粗砂,並設定不同坡度的渠道、不同濃度的水砂比(n)以及沖積平台上不同的積水深度進行實驗,藉此觀察沖積扇的型態變化。實驗改變參數為渠道坡度、水砂比(n)、平台積水深度,觀察沖積扇的縱剖面、橫剖面、平面堆積型態與歷程及頂積層(topset)、前積層(foreset)的狀態。縱剖面和橫剖面的堆積高度隨平台積水深增加而增加,堆積長度則相反;在無積水深時,平面堆積範圍最大且扇緣形狀不規則,隨著積水深增加,範圍逐漸縮小且趨於圓弧形;前積層角度因積水深度變深傾向安息角。頂積層角度則是隨水砂比增加或積水深增加而變小。渠道坡度越陡,使沖積扇堆積長度增加、使堆積高度降低,對堆積角度並無直接關係。但是整體而言,渠道坡度相較於水砂比與積水深度對沖積扇的型態影響較不明顯。;Due to the impact of global climate change and fragile geological background, the slope-land disasters such as landslides and debris flows caused by highly intense rainstorms occur more frequently in Taiwan. Alluvial fans at foothills in Taiwan often accommodate villages and infrastructures, and are high-risk areas prone to the landslides and debris flows. In this study, the formation and the process of alluvial fans is explored by using experimental study with a small-scale flume basin model equipping with silo, laser lights and cameras. By changing the sediment concentration (i.e., the ratio of sediment discharge(Qs) to water discharge (QW)) and the base-level water depths, the longitudinal profiles, cross profiles, fan shapes, angles of topset and foreset angle have been analyzed. The size of the silo opening and particle size control the particle discharge. The longitudinal profiles of the fans depict a concave shape, while the lateral profiles are convex. The angles of topset slope decrease with decreasing sediment concentration, while the foreset slopes with tail water are close to the friction angle of the sediment. Overall, the effect of channel slope on the formation of fan is less than sediment concentration and the base level.
    Appears in Collections:[土木工程研究所] 博碩士論文

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