混凝土联锁排应用于海底电缆防护稳定性研究

海底电缆穿越底质坚硬海床时,覆盖混凝土联锁排可以有效保护海缆。根据国网舟山500 kV海底输电电缆所在海域实测水文数据,采用力学平衡公式和数值模拟两种计算方法,研究混凝土块在极端水流作用下的在位稳定性。基于推导出的力学平衡公式,对其进行函数分析后发现,当混凝土块底边固定时,存在一个极值高度,此时铺设在海床的混凝土块最为稳定,可以抵挡的水流流速最大。通过数值模拟,研究了混凝土联锁排在水流作用下的三维流态特征,对不同形状混凝土块的受力情况进行比较后发现,当混凝土块边缘为圆角时,可以改变边缘周边的水流结构,总体上加强混凝土块的稳定性。经计算,尽管国网舟山500 kV海底输电电缆所在的灰鳖洋海域潮流流速较大,但常规长、宽、高为0.4 m×0.4 m×0.3 m的块体组成的混凝土联锁排可以抵抗水流的冲击,保护海底电缆。

Physical and numerical model study on stability of concrete interlocking mattress for submarine cable protection

When the submarine cable passes through the hard bottom seabed, covering the concrete interlocking mattress can effectively protect it. According to the measured hydrological data in the sea area of the state grid corporation of 500 kV submarine cable project, two methods were used to study the stability of the concrete interlocking mattress under the extreme flow. Based on function analysis of the mechanical balance, it is found that when the bottom length of the concrete block is fixed, there is an extreme height. At this time the concrete block laid on seabed is the most stable, and also the flow velocity that can be resisted is the largest. Through numerical simulation, the three-dimensional flow characteristics of concrete interlocking mattress in current were studied. After comparing the force situation of different shape concrete blocks, it is found that when the edge of the concrete block is rounded, the flow structure around the edge can be changed, and the stability of the concrete block can be strengthened in general. Although the current velocity in the sea area of the state grid corporation of 500 kV submarine cable project is large, the conventional size of 0.4 m×0.4 m×0.3 m blocks can resist the impact of the current and protect the submarine cable.