Response in a porous seabed under dynamic environmental loading is a vital engineering issue in marine geotechnics. Lots of investigations for seabed response under dynamic loading have been developed through mathematical, numerical and experimental approaches. Most previous numerical models for seabed response in marine environments were based on finite element models. In this paper, based on local radial basis function collection method (LRBFCM), a meshfree model is proposed for the seabed response in the marine environments. In the present model, partial dynamic approximation (u-p approximation) will be used, and three different types of natural loading will be considered, i.e., wave, current and earthquake loading.
In the last twenty years, more and more marine structures are constructed with the deeper exploration and study for the offshore area. The most important aspect to be considered in engineering practice is the stability after putting in use of those marine structures under the complicated environment loading. In general, three types of the environmental loading needs to be taken into account for the design of marine structures, which are ocean waves, currents, and probable earthquake respectively. The dynamic response under these loading has attracted great attention among coastal and geotechnical engineers due to the growth of activities in marine environments. As the conventional loading, how ocean wave and current affect the marine structure stability is a vital problem for coastal engineers.
In general, the propagating ocean wave will generate the dynamic pressure in the sea floor, which may trigger soil liquefaction of the seabed as reported in the laboratory test (Sassa and Sekiguchi, 1999). Meanwhile, the effect of earthquake is also important for engineering design. Although the probability of earthquake occurred nearby the marine structures is not so high, once the earthquake happened, the damage would be devastating.
As one of the major natural disasters need to be considered in structure design, earthquake is also able to liquefy the saturated soil through seismic shaking effect. The liquefaction phenomena induced by seismic wave was fully aware by the public from the Niigata earthquake in 1964 in Japan, which caused unprecedented damage. The problem of earthquake-induced liquefaction attracted a great deal of attention of geotechnical researcher and great achievements have been made in the past (Seed et al., 2003). However, as pointed by Ye and Wang (2015), most of the studies for earthquake loading are concerned with onshore structures, while only a few studies considered offshore structures whatever by experiment or numerical simulation. For the earthquake loading, Chen et al. (2018) has developed the analytical solution for layered porous seabed under vertical seismic motion.