水下圆形重力式网箱缆绳张力对波、流的响应特性

Characters of lines tension of submerged circle gravity cage under effects of waves and currents

通过模型试验研究了周长40 m、网高10 m的HDPE圆形升降式网箱沉降在水下时的缆绳张力。试验采用狄克逊准则,模型大比例尺λ=10和小比例尺λa=λd=2;网箱采用网格形式锚泊系统。试验时前主缆绳水平方向与波流夹角为0°,试验流速为0、5、10和15 cm/s,波浪周期范围1.3~2.2 s,波高范围10~30 cm。在各试验条件下对主缆绳和系框绳以及浮框绳张力进行了测试,以受力最大的缆绳为研究对象,分析了缆绳最大张力与波流因子之间的关系。结果显示:①在纯流作用下,前主缆绳受力最大;在纯波作用下,后侧主缆绳受力最大,最大张力随波高增大呈线性增长趋势,随周期变化的影响较小。②在波流作用下,高流速、低波高、高波周期条件时前主缆绳受力最大;在低流速、高波高、低波周期时后侧主缆绳受力最大;前主缆绳受水流作用影响较大,后侧主缆绳受波浪作用影响较大。③在波流作用下,各缆绳最大张力随波高、流速增大而增大,随周期增大而减小;后侧主缆绳最大张力无量纲量随波陡增大且基本呈线性增长趋势。

In the paper,the characters of tension in the mooring lines of a single HDPE gravity cylindrical cage under water are studied by experimental tests.The prototype of cage has a perimeter of 40m and a net height of 10m.Based on the Dixon rule of gear tests,two scales are chosen for the experimental model,i.e.λ=10 andλa=λd=2.The horizontal projections of the front mooring lines are in the same direction of current or incident waves.Uniform current is produced in the whole basin at a velocity of 0 cm/s,5 cm/s,10 cm/s and 15 cm/s.Regular waves with a period within the range of 1.3 s to 2.2 s and a height varying from 10 cm to 30 cm are generated.Tensions in the mooring lines are measured.The following conclusions might be drawn from the analysis of measured data.(1)Under the actions of current only,the average tension in the front main cable is greater than that of other lines.Under the actions of waves only,the maximum tension in the rear side main cable is greater than that of other lines.The maximum tension is linearly related to the wave height.The maximum tension of the front main line decreases with the increase of the period.(2)Under the combined effects of waves and currents,the maximum tension in the front main line is greater than that of other lines under high flow velocity,low wave height and high wave period;the maximum tension in the rear side main line is greater than that of other lines under low flow velocity,high wave height and low wave period.(3)Under the combined effects of waves and currents,the maximum tension of each line increases with the increase of the wave height,the increase of the flow velocity,and the decrease of the wave period.