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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/71131

    Title: 滲流引致渠床顆粒堆積之潰散過程分析
    Authors: 黃子益;Huang,TZU-I
    Contributors: 土木工程學系
    Keywords: 土石流;顆粒流;堆積體;速度剖面;衝擊力;debris flows;granular flow;seepage failure;velocity profile;Bagnold;impact force
    Date: 2016-07-22
    Issue Date: 2016-10-13 12:08:04 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 本研究進行堆積體受滲流作用進而發展成顆粒流之渠槽實驗,利用高速攝影機所拍攝之影像進行影像分析,並給定堆積體上游有固定供水量情況下,堆積體內部因滲流作用產生的破壞行為及後續潰散為顆粒流的運動特性。在速度分析是利用PIV技術中Voronoï Patterns方法來分析顆粒流速度剖面,比較在不同的上游供水量及底床坡度的速度分布,並和Bagnold速度理論進行比較。本研究並以水壓計量測衝擊顆粒流撞擊垂直平板的壓力,並與前人經驗公式比對,討論實驗中可能導致壓力峰值誤差及不準確性。
    顆粒流之波峰高度會隨著供水量及坡度不同而有所改變,顆粒流內部的含水程度亦會影響其速度。顆粒流運動速度在坡度15度較符合Bagnold Profile之條件,且底部有滑脫速度產生。實驗中利用水壓力計進行量測,無法準確地反應出其衝擊力大小,與於理論值相比,有低估情形,其原因可能為顆粒流的前鋒並非飽和狀態,且顆粒的撞擊力無法完全轉換為擋板上之水壓力。
    ;The mobilization process of a granular pile and the associated debris flow by the action of upstream runoff and seepage was experimentally investigated in an inclined flume. The critical condition and the failure process of the granular pile were analyzed by employing the PIV approach. The effect of runoff discharge, flume slope and permeability are explored. During the mobilization process, a partially unsaturated granular snout was formed, then became a bulge at the surge front just as stony debris flows in the field. The velocity profile in the unsaturated snout depicts a Bagnold’s rheology, but it deviates slightly from Bagnold’s profile due to presence of bottom slipping in the intermediate saturated zone. In addition, the evolution of solid fraction indicates that the critical failure condition is controlled by the seepage flow. The pore pressure sensors couldn’t accurately reflect the magnitude of impact force upon the vertical wall since the approaching granular flow is unsaturated and the particle impact can not be fully transformed into the dynamic pore pressure.
    Appears in Collections:[土木工程研究所] 博碩士論文

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