水深条件对单桩基础局部冲刷和流场结构的影响

Effects of the relative water depth on the local scour and flow structures surrounding a monopile foundation

在清水条件下,对单桩基础周围的局部冲刷和流场结构进行了三维数值模拟研究。结果表明,冲刷深度、冲刷坑尺寸和流场结构受相对水深(h/D=0.5~2.5)的影响显著。随着h/D的减小,单桩周围的冲刷深度单调递减,且桩前和桩后冲刷深度的减小幅度大于桩侧的减小幅度;随着h/D的减小,桩前半径和桩侧半径均单调递减,但桩侧半径的变化速率略慢。这些变化趋势均与桩前马蹄涡和下降流动以及桩后上升流动随相对水深的减小明显减弱有关。此外,相对水深较小时,冲刷坑下游的尾涡更贴近床面,导致下游堆积体的高度较低。

Under clear-water conditions,a three-dimensional numerical simulation of the local scour and flow structures around a monopile foundation was carried out.The results show that the scour depth,scour pit dimensions,and flow structures are significantly affected by the relative water depth(h/D=0.5-2.5).With the decrease of h/D,the scour depth decreases monotonously,and the decrease of the scour depth in front of and behind the monopile is greater than that at the sides of the monopile.The front and side radius of the scour pit monotonically decreases with h/D,but the decreasing rate of the side radius is slightly lower.All these trends are related to the weakening of the horseshoe vortex,the descending flow in front of the pile,and the ascending flow behind with the decrease of h/D.In addition,when the relative water depth is low,the wake vortices downstream of the scour pit are closer to the bed surface,resulting in a lower height of the downstream deposition.