Hydro-mechanical modelling of interaction between monopiles and cross-anisotropic sandy seabed subjected to wave loadings

Cross-anisotropy is a typical feature of marine sediments. To explore the monopile-seabed interaction in cross-anisotropic sandy seabed subjected to wave loadings, a hydro-mechanical model is established and the nonlinear monopile-soil contact behaviours such as slip and separation are considered. It is shown that, when the seabed properties in the horizontal plane were kept constant, the increase of seabed anisotropy results in three effects: A) the decrease of vertical coefficient of permeability k(V), B) the increase in vertical elastic modulus E-V and shear modulus G(V), and C) the decrease of Poisson's ratio mu(HV). Effect A will lead to a reduction of excess pore water pressure and an aggravation of momentary liquefaction around the monopiles. Effect B is conducive to the decrease of lateral displacement and bending moment of the monopiles. Besides, wave-induced settlement of the monopiles is observed and is found to be alleviated by effect B.

Automated summary

A hydro-mechanical model is established to investigate the monopile-seabed interaction in cross-anisotropic sandy seabed under wave loadings, considering the nonlinear behaviors of slip and separation between monopile and soil. The results show that increasing seabed anisotropy leads to a decrease in vertical coefficient of permeability, an increase in vertical elastic modulus and shear modulus, and a decrease in Poisson's ratio. These effects have implications on excess pore water pressure, momentary liquefaction, lateral displacement, bending moment, and wave-induced settlement of monopiles.