Uplift of immersed tunnel in liquefiable seabed under wave and current propagation

Abstract

In ocean environments, wave usually propagates in association with a current. The paper presents a cyclic characterization framework for elastoplastic consolidating behavior of liquefiable seabed around the immersed tunnel under combined wave and current loading, based on the Biot dynamic consolidation theory. Special attention is placed on modeling the nonlinear wave-current interaction, the cyclic plasticity behavior of marine deposits and the soil-structure contact effect. The paper extends an existing Masing model to large strain regime (in the order of 10−2) in the framework of cyclic plasticity for capturing the liquefaction-induced nonlinear behavior of marine deposits. Then the proposed cyclic plasticity model is implanted into an explicit time matching finite difference analysis platform, permitting a comprehensive simulation of the intensive response of the immersed tunnel in the seabed experiencing the excess pore pressure accumulation and residual liquefaction. Retrospective simulation of a well-documented centrifuge test by the proposed framework indicates satisfactory agreement, validating the reliability for capturing the excess pore pressure accumulation and residual liquefaction during wave propagation. Finally, the influences of current on the wave-induced liquefaction in the vicinity of an immersed tunnel are investigated by a numerical example. The results indicate that the ocean current significantly changes the original characteristics of wave-induced liquefaction as well as the induced uplift of the immersed tunnel, especially with consideration of the cyclic plasticity behavior of marine deposits. The mechanisms of seabed liquefaction and the induced uplift of the immersed tunnel under wave and current actions are also interpreted