Local scour around a porous surface-piercing square monopile in steady current
Local scour around a porous surface-piercing square monopile in steady current
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DOI：
10.1016/j.oceaneng.2021.108716
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发表时间：
2021-03
影响因子：
5
通讯作者：
Fan Yang;Li-yan Qu;G. Tang;Lin Lu
中科院分区：
文献类型：
--
作者：
Fan Yang;Li-yan Qu;G. Tang;Lin Lu
通过实验研究了恒定水流作用下方形截面多孔单桩的局部冲刷。在活床流动条件下，不同攻角(α=0°~60°)的孔隙度变化(P=0~38.8%)。系统地研究了冲刷发展的时程、平衡冲刷深度、时间尺度和冲刷坑剖面。沿流孔隙度的增加大大削弱了上游单体桩内的马蹄涡，导致冲刷深度减小。然而，横向孔隙度对单体桩周围的局部冲刷的贡献有限。对于攻角α=30°和45°的多孔独柱，由于角部速度放大系数的突然增大，出现了二次冲刷。此外，还研究了石层防护作为多孔单体桩周围局部冲刷防护措施的有效性。冲刷坑的特征已被量化。结果表明，碎石层能有效地消除冲刷坑。特别是，防护层的直径或高径比越大，对策的有效性越大。
Local scour around a porous monopile with the square cross-section in steady current is investigated experimentally. A variety of porosity (P= 0–38.8%) is explored alongside with different attack angles ranging from α= 0°–60° in the live-bed flow condition. Time history of the scour development, equilibrium scour depth, time scale and the scour hole profile have been systematically studied. The increase of the streamwise porosity is found to largely weaken the horseshoe vortex in the upstream monopile and leads to a decrease of scour depth. However, the transverse porosity has limited contribution to the local scour around the monopile. A secondary-scour is revealed for the porous monopile with attack angles α= 30° and 45°, which is due to the sudden increase of the velocity amplifications at the corner of the monopile. The effectiveness of stone layer protection as countermeasure against local scour around a porous monopile has also been studied. The characteristics of the scour hole have been quantified. It is showed that the stone layers can effectively eliminate the scour hole. In particular, the larger the diameter of the protection layers or the height-to-diameter ratio, the greater the effectiveness of the countermeasure.