近海欠密实砂质海床内波致渐进液化特征研究

Investigation on the wave-induced progressive liquefaction of offshore loosely deposited sandy seabed

利用一个经过广泛验证的数值模型FSSI-CAS 2D为计算工具,采用砂土的高级本构模型Pastor-Zienkiewicz-Mark III(PZIII)描述海床砂土的动态力学行为,定量研究松散海床地基土在波浪作用下,其内部的液化过程和特征,以加深对波致海床液化特征、性质的认识。计算结果分析表明,开发的耦合数值模型FSSI-CAS 2D能够很好地捕捉到波浪作用下欠密实海床的动力响应特征,以及海床内的累积液化过程等一些列的非线性物理现象。研究表明,波浪导致的松砂海床液化是一个渐进过程,海床表面首先液化,并逐渐向下扩展。

The Pastor-Zienkiewicz-Mark III（PZIII） constitutive model, which can be used to describe the nonlinear behavior of sandy seabed soil, is implemented into a well-validated computer code, FSSI-CAS 2D, for analyzing the wave-seabed-structure interaction. The characteristics of wave-induced liquefaction in offshore loosely-deposited sandy seabed is quantitatively investigated. The analysis results indicate that the developed coupled numerical model FSSI-CAS 2D is capable of capturing a series of the properties of wave-induced cumulative liquefaction in loose seabed, as well as its wave-induced dynamics. The results also show that the wave-induced liquefaction in seabed is progressive. That is, wave-induced liquefaction initiates at the surface of seabed, and propagates downward under long-term wave loading.