Numerical Analysis On The Dynamic Interaction In Structure-Wave-Seabed Coupling System

In the field of harbor and offshore engineering, the structure-wave-seabed coupling system can often be found in some structures such as dock, breakwater and bucket foundation platform. This kind of structure keeps its stability, under the force of wind, current, ice and random wave, by deeply embedded in the seabed. Study on the mechanism of instability and failure of this kind of structure is an unsolved topic and a research full of challenge in the field of numerical analysis. Interface does exist in the structure-wave-seabed coupling system and there is no doubt that interface is a very import aspect in the numerical analysis because energy is transferred by it between the structure and seabed. In the field of numerical analysis of geotechnical engineering, contact elements, such as Goodman element and Desai element, are often used to solve the contact problems. But there are some limits and many difficulties in numerical methods by using this method to solve contact problems. For the aim of investigating the effects of interface on the coupling system, a finite element model of it is established based on the wave flume experiments and a static analysis is carried out by employing the D-P model of soils. The method of direct restriction offered by MSC.Marc software is used to solve the contact problem and good results are acquired in this paper.The results of static analysis demonstrate that even if the effects of interface are taken into account, the reasons for instability and failure of the structure can still not be elucidated. It's because that soils behave themselves with the characteristics of nonlinear deformation, degradation of strength and cumulation of plastic deformation under cyclic dynamic load. So it's very necessary to perform a dynamic analysis on the coupling system by employing dynamic constitutive relation of soils. For this purpose, the widely used equivalent linear model and equivalent linear algorithm in soil dynamics are introduced into the MSC.Marc software for the first time by second development and dynamic analysis on the coupling system is carried out. The results of dynamic analysis are compared with that of static analysis and the effects of interface on the coupling system in dynamic analysis are further investigated. Results of this paper lay a good foundation for the dynamic instability study of this kind of structure.