波流作用下淹没圆柱局部冲深影响因素分析

淹没圆柱在海洋工程中运用广泛，局部冲刷对此类建筑物的安全有较大影响。为掌握该类型建筑物在波流作用下的冲刷特性，在波流水槽内开展了一系列试验研究。试验将圆柱模型安装在波流水槽中部的沙槽内，沙槽内铺设中值粒径0.22 mm的无黏性沙，形成平底海床。试验中圆柱处于淹没情况，改变入射波流条件，观测多种波流作用下，不同高度淹没圆柱周围的局部冲刷深度发展过程，分析了多种无量纲参数对局部冲刷深度的影响。结果表明:当KC数不变时，冲刷深度s/D随着相对流速U_cw和Fr的增大而增大，当Fr增大到一定程度时(Fr>0.80)，冲刷深度s/D趋于稳定; U_cw在固定范围内时，冲刷深度s/D随KC数的增加而增加，增长速率逐渐变慢; 引入淹没因子K_s，得到了淹没圆柱与非淹没圆柱的冲刷深度计算关系式。

Research on the influencing factors of scour depth around submerged cylinder under combined action of wave and current

Submerged cylinders are widely used in marine construction. Local scour has a great impact on the safety and stability of such buildings. In order to understand the scour characteristics of this type of building under wave and current, a series of scour experiments were carried out in the wave-current flume. The model was installed in a flat sand box in the middle of the wave-current flume, of which the surroundings were covered with non-cohesive sand of median diameter 0.22 mm. The water level is always set as submergence situation. The condition of incident wave and current was changed to observe the local scour development process around the submerged cylinder with various heights. The local scour depth was measured and recorded. A variety of dimensionless parameters were applied to analyze the data and assess their influence on the scour. The result shows that when KC number is fixed, the relative scour depth s/D increases with the relative flow velocity Ucw and Fr. When Fr increases to a certain extent (Fr>0.80), s/D tends to be stable; when Ucw is in a fixed range, depth s/D increases with KC number, and the growth rate gradually becomes slower. The submergence factor Ks gives the relationship between the scour depth of the submerged cylinder and that of the non-submerged one.