近岛礁地形影响下的浮式平台运动响应

近岛礁附近的地形一般呈现高低不平的状态,水深从几十米到几米不等。远场波浪向近岸传递过来时在礁盘上会经过复杂的演化,使得浮体附近的波浪呈现一定的非均匀性,不同于常规的长峰规则波,同时礁盘的起伏变化会对波浪中的浮体的运动产生影响,最终使得浮体在复杂地形下的水动力运动响应不同于一般均一水深下的浮体响应。该文通过建立浮体和礁盘地形的耦合水动力模型,计算了礁盘对浮体入射波力、绕射力、辐射水动力系数以及运动的影响,同时与水池模型试验对比了浮体运动,两者较为一致。研究表明复杂地形对浮体的水动力运动存在较大的影响,在某些周期附近会增大浮体的运动响应,因此需要理性考虑复杂地形对浮体的影响。

Motion responses of floating structures near small islands

The seabed topography near small islands is usually in rugged state, and the water depth can be changed from tens of meters to a few meters in a short distance. Far field waves advancing towards the shore will experience a complex evolution on the shoal. In this environment, the hydrodynamic responses of a float-ing structure will be largely affected by the non-uniform wave pattern and changeable seabed, and might be quite different from the general responses of a platform in waves with uniform water depth. In this paper, a coupling hydrodynamic model of floating structures and reef topography was established; the incident wave force, diffraction force, radiation hydrodynamic coefficients, motions of a floating structure were calculated. The model was validated by comparing the predicted results with those of model tests. It is indicated that complex sea bed topography has a significant influence on the hydrodynamic responses of the floating structure. Moreover, the motions are increased obviously in certain wave periods, with reference to that in far field waves.