A study of the vibration properties of a pile-net structure under wave-induced excitations

Pile-net enclosure structures for aquaculture in marine environments usually consist of flexible nets suspended between piles anchored to the seabed. These structures often experience simultaneous vibrations due to wave action. In this study, a coupled dynamic model is developed to simulate the three-dimensional vibrations of a pile-net structure constrained by seabed soil and subjected to wave excitations. The waves are simulated using Stokes second-order wave theory. The piles are modeled with Euler-Bernoulli beam theory, and the seabed soil is represented by spring models. The vibrations of the flexible net are simulated using the lumped-mass method. The Morison equation is applied to calculate wave-induced hydrodynamic forces on the piles and net. With comparisons to the results of the finite element method and experiments, the present dynamic model is validated. The vibration properties of a pile-net structure are analyzed, and several parametric studies are conducted to evaluate the impacts of pile diameter, pile length, soil spring stiffness, and wave direction. The results demonstrate that the pile-net structure will be more strongly constrained and the dynamic responses will decrease as the pile diameter increases, the pile length in seabed soil increases, or the seabed soil becomes more rigid.