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題名 | 石流撞擊機制之試驗分析=Experimental Analysis on Impact Mechanism of Granular Flows |
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作者姓名(中文) | 劉格非; 李峰昌; | 書刊名 | 力學 |
卷期 | 13:1 1997.03[民86.03] |
頁次 | 頁87-100 |
分類號 | 434.273 |
關鍵詞 | 石流; 撞擊力; Granular flow; Impact force; |
語文 | 中文(Chinese) |
中文摘要 | 本研究以實驗方法,藉助室內大型試驗渠槽,並引進數位影像處理系統之流場顯 影儀,觀測並量測快速的土石流運動,改進以往學者在模擬土石流實驗時,無法精確有效地 測量到土石流前鋒速度、瞬時速度流場與密度等問題。 首先由質量連續方程式與動量守恆方程式,推得土石流流動之控制方程式。並由流體力學控 制體積的觀念,推得土石流對攔阻壩之作用理論表示式。可知土石流對攔阻壩的作用力包括 土石流靜壓效應、動壓效應、重力效應、剪力效應以及震波效應等項。再藉由實驗之模擬測 量分析知,土石流撞擊到壩體時對壩體作用力之變化情形,剛開始撞擊瞬間,撞擊力由震波 及動壓差主導,之後便漸改由靜壓主導。震波作用於壩體後有反彈現象,導致壩體受力強烈 振盪。理論推導所得值與試驗所得相當吻合。 其它密度、波速、流場等的結果亦可使這方面之研究學者對土石流之流動狀況有更深之瞭解 。 |
英文摘要 | We use sand with equivalent diameter between 3.36mm to 4mm to simulate debris flows. Sand piling area has a length 2m, height 0.5m and width 0.5m. At the end of a 10m long flume, a plexiglass plate is used as dam. Measuring equipment used include flow visualization equipment for velocity field, phase speed and density, video camera, three mulitidirection load cells, one stress cell and one pressure cell. Signals is triggered by the unblocking of a red-light beam. All signals go through a 12 channel recorder then recorded by a PC. The maximum pressure occurs very close to the free surface and can be 1.5 to 2.5 larger than the final static pressure. Maximum stress occurs near the bottom and rises as flow depth increases. The total force exerted on a single high dam is larger than several samll dams. But the mass behind a single high dam is greater. Economic analysis including building and maintainance should be considererd before engineering decision. |
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