Coastal Engineering ( IF 4.4 ) Pub Date : 2020-12-22 , DOI: 10.1016/j.coastaleng.2020.103831 Weidong Yao , Scott Draper , Hongwei An , Liang Cheng , John M. Harris , Richard J.S. Whitehouse
Many subsea structures have non-uniform geometries, which extend only a finite distance above the seabed. To better understand local scour at these structures, this paper presents scour measurements from an experimental study of submerged compound piles comprised of a circular superstructure supported by a circular foundation. The experiments were conducted in the clear-water regime and considered the effect of three different ratios describing the structural geometry: (i) the overall height of the compound structure above the initial bed level to the diameter of the super-structure ; (ii) the height of the foundation exposed above the initial bed level relative to the overall height of the superstructure ; and (iii) the diameter of the foundation to that of the superstructure . In all cases and (i.e. the foundation and superstructure where never buried). The experimental results indicate that, if all other parameters are held constant, the non-dimensional equilibrium scour depth increases with both and , and decreases as increases. To quantitatively explain these trends the experimental results are compared with a range of existing methods to predict scour depth for non-uniform (or complex) surface piercing piles. Of these methods it is found that an effective pile height and an effective pile diameter, computed using simple geometric arguments, give good agreement. The concept of effective height is also shown to collapse time-scale measurements of the scour process convincingly across the full range of experimental results and to explain the extent and shape of the local scour hole reasonably well. Collectively, these findings suggest that the calculation of an effective height may be used to provide a reasonable first approximation to estimate the rate and extent of local scour around submerged compound structures.
中文翻译:
恒流下浸没式复合桩周围局部冲刷试验研究
许多海底结构的几何形状不均匀,仅在海床上方延伸有限的距离。为了更好地了解这些结构的局部冲刷情况,本文提供了对沉浸式复合桩的实验研究得出的冲刷测量结果,该桩由圆形基础支撑的圆形上部结构组成。实验在清水条件下进行,并考虑了描述结构几何形状的三种不同比率的影响:(i)初始床层以上的复合结构的总高度到上部结构的直径; (ii)相对于上层建筑总高度而言,暴露在初始床层上方的地基高度; (iii)地基直径至上层建筑直径。在所有情况下 和 (即从未埋藏的基础和上层建筑)。实验结果表明,如果所有其他参数保持不变,则无量纲平衡冲刷深度 两者都增加 和 ,并减少为 增加。为了定量解释这些趋势,将实验结果与各种现有方法进行比较,以预测非均匀(或复杂)表面穿孔桩的冲刷深度。在这些方法中,发现使用简单的几何参数计算出的有效桩高和有效桩径具有良好的一致性。有效高度的概念也被证明可以使冲刷过程的时间尺度测量结果在整个实验结果中令人信服,并且可以很好地解释局部冲孔的范围和形状。总的来说,这些发现表明有效高度的计算可用于提供合理的第一近似值,以估计淹没的复合结构周围局部冲刷的速率和程度。