Dynamic and Residual Pore Water Pressure Response of Hybrid Foundation System Under Combined Action of Wind, Wave and Seismic Loading

Abstract

The dynamic response characteristics of the innovative marine wind power hybrid foundation under combined action of wind, wave and seismic loading are studied in this article. Taking the monopile foundation as reference group, the shearing strain-volumetric strain coupled pore pressure incremental constitutive model was utilized to simulate the kinetic behavior of seabed’s saturated soil. The pressure distribution and variation characteristics of residual pore water pressure around pile foundation due to the interactions of upper structure, foundation and saturated soil are illustrated. The results indicate that: (a) the cylindrical platform changes the residual pore water pressure and accelerates the pressure accumulation area, which converts from surrounding the monopile to nearby the cylindrical platform; (b) compared to the hybrid foundation, the peak value of residual pore water accumulation of the monopile foundation is smaller only under seismic loading, which is due to that the monopole with smaller stiffness is more vulnerable to deform with soil synergistically; (c) the cylindrical platform structure can significantly reduce the horizontal placement extreme of pile foundation under the action of dynamic load, and can also change the distribution characteristics of bending moment of middle pile of the hybrid foundation. It is manifested by a lower bending moment extreme of the middle pile near the mudline under the action of wind and wave loading, while the seismic loading could increase the bending moment extreme of middle pile near the mudline.