波浪荷载下海底单桩与土共同作用的数值分析
Numerical analysis of interactive behavior between pile and seabed soil under wave load
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摘要: 采用三维数值分析方法研究了波浪荷载作用下饱和海床与埋入单桩的相互作用特性,考虑了海床饱和土体的流固耦合和桩土界面的接触特征,并采用准静态方法模拟短峰波作用于海床的三维波压力分布与变化特征。根据数值分析结果,研究了波浪荷载作用下海床土体内的孔压和应力变化规律、海底单桩的变形和内力分布情况,探讨了桩土接触面不同处理方式的影响,并与自由海床的结果进行比较。结果表明桩端附近土体的孔压出现局部放大现象,桩身水平位移主要受土体位移影响。采用桩土耦合模型将夸大土体内的附加应力和孔压变化,且桩身内力和桩底的应力集中现象也更为明显。Abstract: An FEM model for a single pile embedded in a saturated seabed is proposed to study the interactive behavior between pile and seabed soil. Fluid-soil coupling and contact behavior on interface is considered, and the quasi-static method is adopted to simulate the crested short wave-induced load on seabed surface. Based on the numerical results, responses of pore water pressure and stress seabed soils under the wave load are investigated, and the deformation and internal force of the single pile are discussed. Two different methods to simulate the pile-soil interface are discussed with a comparison to the greenfield seabed model. The results show that the pore water pressure increases obviously near the bottom of pile, and the lateral displacement of pile is mainly affected by soil. Moreover, the pore water pressure and stress are overestimated by the pile-soil coupled model, and the stress concentration at bottom of pile is more obvious than that by the pile-soil contact model.