ABSTRACT

The evaluation of the wave-induced residual pore pressure in a porous seabed is vital for the prediction of the potential of seabed instability, which is particularly important for the design and construction of marine infrastructures foundations. The existing models for the residual liquefaction have been limited to the quasi-static uncoupled approach, which ignores the inertia effects due to the acceleration of solid particles and pore fluid. In this paper, a new model for residual soil response with up approximation (Partial dynamic model) is proposed and coupled with oscillatory mechanism. The new model will be validated with the wave flume tests. Based on the coupling model, a new criterion of liquefaction is proposed to include both oscillatory and residual mechanisms. Numerical examples demonstrate the significant impact of coupling effects on the wave-induced seabed liquefaction.

INTRODUCTION

In general, based on field measurements and laboratory experiments, two mechanisms of the wave-induced seabed liquefaction have been reported in the literature (Sumer & Fredsøe, 2002; Jeng, 2012). They are: oscillatory liquefaction and residual liquefaction. The first mechanism is resulted from the transient or oscillatory excess pore pressure and accompanied by attenuation of the amplitude and phase lag in the pore pressure (Yamamoto et al., 1978; Hsu & Jeng, 1994), which appears near wave trough (Jeng, 2012). The second mechanism is caused by the build-up of excess pore pressures under action of cyclic loading (Seed & Rahman, 1978; Sumer & Fredsøe, 2002).

Numerous investigations for the wave-induced residual liquefaction have been carried out (Seed & Rahman, 1978; Jeng & Seymour, 2007; Jeng & Zhao, 2015; Shanmugasundaram et al., 2021). These investigations have been based on Biot's consolidation model (Biot, 1941), which is quasi-static approach. In this type of approach, the accelerations caused by soil and fluid particles are not considered, which is important for certain combination of wave and seabed conditions. Based on Biot (1956) and Zienkiewicz et al. (1980), Jeng et al. (1999) proposed the first up approximation for the wave-induced oscillatory soil response. To date, there is no up approximation for the wave-induced residual liquefaction available in the literature.

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