波浪作用下海床的稳定性与液化分析

STABILITY AND LIQUEAFACTION ANALYSIS OF SEABED TO WAVE LOADING

波浪作用下海床的稳定性与液化分析是海底管线、防波堤和海洋平台设计中必须仔细考虑的问题。本文推荐了一个循环荷载作用下土体的弹塑性实用本构模型，并给出了一种粉土的模型参数。该模型直接根据初始应力状态和循环应力的大小与作用时间计算土体的塑性应变增量，在有限元计算中不需要引入弹塑性矩阵。采用Biot理论和有限单元法，计算了粉土海床在波浪作用下的孔隙水压力和有效应力的变化过程，并对海床的稳定性和液化进行了分析。计算结果与波浪槽实验反映的规律是相符的。

Stability of seabed in response to ocean wave loading is an important consideration in the design of offshore structures. To describe the strain characteristic of cohesionless soils under cyclic loading, a framework of a practical constitutive model is proposed and model parameters of a silt are obtained mainly from un-drained dynamic triaxial tests. Plastic strain of soils under cyclic loading can be calculated from initial stresses state, cyclic stresses and its duration in the process of FEM calculation, and the elasto-plastic matrix relating stress and strain is not needed. Biot’s consolidation equation is applied in the FEM Program developed by the authors. Variation of effective stresses of silt seabed response to progressive waves is given. Numerical results agree well with the wave tank test results in trend.