Scour Downstream of an Apron Due to Submerged Horizontal Jets
Scour Downstream of an Apron Due to Submerged Horizontal Jets
复制标题
淹没水平射流冲刷停机坪下游
DOI：
10.1061/(asce)0733-9429(2006)132:3(246
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发表时间：
2006
影响因子：
2.4
通讯作者：
A. Sarkar
中科院分区：
文献类型：
--
作者：
S. Dey;A. Sarkar
本文介绍了一个试验研究的结果，该试验研究是关于泄洪口淹没水平射流对护坦下游非粘性沉积物（均匀和非均匀沉积物）的冲刷。试图解释冲刷过程和剖面（包括冲坑下游沙丘）中存在的相似性。不同时刻的冲刷剖面具有一定的几何相似性，可以用两个多项式的组合来表示。利用不同时刻的实测冲刷深度，得出了冲刷深度随时间的变化规律，即时间尺度与密度弗劳德数呈线性关系。平衡冲刷深度与相对于闸门开度的泥沙粒径有关，随泥沙粒径和闸门开度的增大而减小。另一方面，平衡冲刷深度随着密度弗劳德数的增加而增加。平衡冲刷深度随尾水深度的变化表明，临界尾水深度对应于最小平衡冲刷深度。沉积物级配对冲刷深度的影响对于不均匀沉积物来说是显著的，由于形成了装甲层，从而显著降低了冲刷深度，因此促使研究了刚性护坦下游的下水护坦对冲刷深度的降低作用。试验结果表明，设置导水板后，平均减沙率为39%，最大减沙率为57.3%，最小减沙率为16.2%。通过物理推理和量纲分析，确定了影响最大平衡冲刷深度的特征参数。根据经验公式得出的最大平衡冲刷深度公式与试验结果吻合较好。
The results of an experimental investigation on scour of noncohesive sediment beds (uniform and nonuniform sediments) downstream of an apron due to a submerged horizontal jet issuing from a sluice opening are presented. Attempts are made to explain the similarity existing in the scour process and profiles (including dune in the downstream of the scour hole). The scour profiles at different times follow a particular geometrical similarity and can be expressed by the combination of two polynomials. Using experimental scour depth at different times, the time variation of scour depth is scaled by an exponential law, where time scale increases linearly with densimetric Froude number. The equilibrium scour depth, related to the sediment size relative to the sluice opening, decreases with increase in sediment size and sluice opening. On the other hand, the equilibrium scour depth increases with increase in densimetric Froude number. The variation of equilibrium scour depth with tailwater depth indicates a critical tailwater depth corresponding to a minimum equilibrium scour depth. The effect of sediment gradation on scour depth is pronounced for nonuniform sediments, which reduce scour depth significantly due to formation of an armor layer, and therefore prompted study of the reduction of scour depth by a launching apron placed downstream of the rigid apron. The results show that the average reduction of scour depth by placing a launching apron was 39%, having a maximum of 57.3% and a minimum of 16.2%. The characteristic parameters affecting maximum equilibrium scour depth are identified based on the physical reasoning and dimensional analysis. Equation of maximum equilibrium scour depth obtained empirically agrees well with the experimental data.