Numerical Evaluation for Dynamic Response of Seabed Under Random Wave Loading

The analysis of dynamic response of seabed due to wave loading is of practical significance in design and construction of marine structures and offshore installations. Recently considerable efforts for this problem have been made with growing interest by many researchers and marine engineers, and many representative results have been achieved. It is obvious that wave loading plays a significant role in the evaluation of construction safety and seabed instability. But there are few results of research and engineering design that can consider the feature of wave loading and soil parameters together. The purpose of this paper is to establish a reasonable numerical model to simulate dynamic response of seabed under random wave loading. The dynamic relation between random wave and seabed can also be described through this model. Comparative studies are principally made between the proposed analysis considering actual feature of ocean situation and conventional analysis based on linear theory of regular wave. The effect of randomness of wave loading on the dynamic response of seabed is investigated. The necessity is also discussed about considering the influence of damping energy on propagating wave by porous seabed. In the conventional analyses of seabed dynamics, wave loading is basically treated as a deterministic process and is usually taken into consideration by using linear theory of regular wave. In fact, ocean wave is of intrinsic randomness in both time sequences and spatial distribution. The random nature of both wave and wave-induced loading will subsequently affect dynamic behavior of seabed. In this paper, the analyses which can consider characteristics of randomness of wave loading and dynamic interaction between seabed and random waves, are formulated in a stochastic framework. Integrated numerical analysis model is established by employing wave spectrum of AVERAGE JONSWAP. The comparative studies are conducted among the methods of conventional random analysis, proposed random analysis, and linear regular wave theory. The results show that the amplitudes of dynamic response of seabed subjected to random wave loading are larger than that of regular linear wave loading. Therefore the stochastic feature of wave loading has to be duly taken into account in the analysis for dynamic response of seabed.