Dynamic characteristics of a sandy seabed under storm wave loading considering the effect of principal stress rotation

Abstract

This paper aims to investigate the cyclic characteristics of soil under storm waves with the typical irregular character, in which a generalized plasticity model considering the effect of principal stress rotation (PSR) was adopted to model soil behavior. In the present model, the plastic strain generated by principal stress rotation was considered to be an additional item in the constitutive relationship of soil, and the normalized loading and plastic flow directions were determined based on the stress tensor invariants. Comparisons between the present model, previous hollow cylinder apparatus (HCA) tests, and geotechnical centrifugal wave tests all show good agreement. Numerical results indicate that the moveable and random characteristics of the storm wave result in similar and irregular dynamic responses in sandy deposits along the extension direction of the seabed. Moreover, the severest wave loading in a real storm will significantly magnify both the speed and extent of liquefaction of the sandy seabed. Numerical results also demonstrate that ignoring the PSR involved in the storm–wave–seabed interaction will significantly underestimate the build-up of pore water pressure. Additionally, when considering the impact of PSR, the sandy seabed exhibits higher liquefaction resistance when subjected to the random wave compared to the representative regular wave. However, since the sharply weakening liquefaction resistance of soil under the severest wave condition cannot be captured with the regular wave, it is suggested that the random wave be adopted to further investigate the storm–wave–seabed interaction. Parametric studies show that soil properties (e.g., permeability and saturation) significantly affect the liquefaction characteristics of soil under storm waves.