An integrated model for spatiotemporal interaction between bottom-founded offshore fish cage and clayey seabed due to wave loads

Abstract

Bottom-founded offshore fish cages are increasingly becoming popular in recent years in order to meet the world's growing demand for seafood products. Current design practice strongly relies upon the quasi-static maximum load combined with classical bearing capacity theory. Due to the complexity of the soil behavior under cyclic wave action, the quasi-static design philosophy does not guarantee complete safety of the design. The soil strength can be reduced by cyclic loads, potentially leading to failure of cage foundation. This paper proposes an integrated model to simulate the spatiotemporal interaction between the cage and the clayey seabed under wave action, obtaining the time-dependent response of the cage structure. The fluid-structure interaction is governed by the Morison equation and an advanced constitutive model, capturing the cyclic behavior of soil, is adopted for the foundation-seabed interaction. To verify the accuracy of proposed model, the hydrodynamic forces and bearing capacity were validated against analytical solutions, respectively. Both regular wave and irregular wave analysis were conducted to tackle the influence of real sea condition. Furthermore, this paper examined the positive effect of consolidation on soil strength and thereby foundation capacity increases with time during calm sea condition. Based on the proposed integrated model, researchers can more effectively analyze the time-history dynamic performance of fish cages under complex sea conditions.