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題名 | 自由沖射流對防砂壩下游河床局部沖刷現象之研究 |
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作者 | 連惠邦; 蘇重光; 江永哲; 王傳益; | 書刊名 | 逢甲學報 |
卷期 | 26 1993.11[民82.11] |
頁次 | 頁255-267 |
分類號 | 443.92 |
關鍵詞 | 防砂壩; 沖刷深度; 泥砂體積濃度; 土石流; |
語文 | 中文(Chinese) |
中文摘要 | 防砂壩下游河床局部沖刷問題,對壩體安全及河道穩定具有 深遠之影響。因此,本研究由一維運動方程式出發,考慮水流與 床面泥砂間之各種阻抗因素,分別探討當沖刷遠平衡時沖刷坑之 最大沖刷深度,以及沖刷深度隨時間的變化。研究發現沖刷坑內 最大沖刷深度與水流之射流速及床面泥砂顆粒間呈半對數關係, 經與其他研究者試驗資料驗證比較,初步已獲得良好之結果。同 時,本文也以含滓流無因次沖刷方程式模擬估算沖射流之臨界泥 砂體積濃度,結果顯示當水流泥砂含量達此臨界值後,會因水流 本身沖刷能力的降低及下游河床面的阻滯作用,使得沖刷停止, 而產生土砂礫堆積之現象。 |
英文摘要 | Local scour in the channel bed below a sabo dam is an important factor related to river stability and safety of dam body. This paper presents the resuits of a study on the maximum depth of scour hole under equilibrium condition and scouring hydrograph of channel bed. In this study, the resistance factors between sand grain and flow scour were modeled using an one-dimensional motion equation. The results of the study indicated that a semi-logarithmic equation can be used to relate the relative maximum scour depth and the relative plunging jet flow velocity. The derived equation was found to be quite satisfied by comparing with the experiments data obtained from other studies. This study also intends to estimate the critical volume concentration of grain in sediment-laden flow. It is shown that the phenomenon of channel scouring could be replaced by deposition if grain volume concentration of flow reaches its critical value. In addition, the resistance of channel bed will increase when grain volume conentration approaches its critical value. |
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