直立折叶板开孔式沉箱之消波特性初期研究

A Preliminary Study on Wave Dissipation Characteristics of Flap Plate Type of Vertical Caisson

提出一种新型导流式消能结构物的观念,在长方形开孔的内侧加装折叶板,并保留下侧泄水孔。借由波浪及水流运动与折叶板开阖的互动关系,于波峰作用时,推开折叶板让水流进入结构物体内,而在波谷作用时,向外排出的水体力与折叶板重量让折叶板闭合,阻止水流由原路径排出,而改道由下方排水。以水工模型反射率实验方式证明此种新型结构物的消波效果:在设定模型缩尺1/36下,造波周期0.8~3.0s间的反射率均在0.6以下,其中1.0~2.8s都在0.4以下,而1.3~2.5s则都在0.2以下。所以本新型结构物有益于削减港内长周期的波动现象。

A conception of a new type perforated caisson,i.e.a flap plate type vertical caisson,is proposed.A series of flap plates are installed at the inner side of the rectangular openings of the caisson and the openings at the bottom of the caisson are kept as the drain holes.By interacting between the open and close of the flap-plates and the motions of waves and currents,the flap plates are opened in the action of wave crest and water flows into the caisson.And in the role of wave trough the flap plates are closed by both the outward drained water flow and the weight of the flap plate,and the flow of water is prevented from its original path and forced to discharge through the holes at the bottom of the caisson.In such a mechanism,the reflections induced by the scatter waves can be deducted and the wave dissipation ability of the caisson can be improved.The wave dissipation effect of the new caisson is verified by means of the reflectivity experiments carried out by using a hydraulic model.By setting the reduced scale of the model to1/36,the reflection coefficients of the flap plates are all smaller than 0.6 for the wave period ranging from0.8 sto 3.0 s,smaller than 0.4 for the wave period from 1.0~2.8 s,and smaller than 0.2 for the wave period from 1.3~2.5 s.It is shown that this new flap plate type vertical caisson has a very good performance for reducing the long period wave phenomena within the harbor.