深水高桩承台基础地震动水效应数值解析混合算法

A Numerical-Analytical Mixed Method of Hydrodynamic Effect for Deep-Water Elevated Pile Cap Foundation under Earthquake

摘要:

本文针对桥梁深水高桩承台基础—水体耦合动力问题，首先建立了深水高桩承台基础简化数值分析模型，针对桩身，给出了基于水下桩基尺度的桩身动水附加质量解析算法，并计入群桩效应的影响；针对承台，提出了动水附加质量简化有限元计算方法，依靠基于势流体单元的合理的流体动力学数值表达，即考虑了承台真实几何尺寸，又兼顾了其振动周期对承台动水效应的影响，从而得到了地震作用下高桩承台基础地震动水效应数值解析混合算法。以四桩高桩承台试验模型为研究对象，利用本文方法进行模态及时程分析，通过与试验及其他数值、解析结果比较，表明本算法与试验及完全数值方法吻合良好，其计算精度与计算效率得到有效改善。论文对深水高桩承台基础的抗震分析和设计具有参考价值。

Abstract:

This paper focused on the dynamic analyses of the deep-water elevated pile foundation in contact with water. A simplified analysis model of the pile foundation considering the hydrodynamic effect is proposed firstly. The numerical-analytical mixed method for earthquake induced hydrodynamic added mass is provided as follows: for piles, an analytical solution based on the scale of the underwater pile is given including the effect of pile group; for cap, a simple finite element method based on the potential-based fluid formulation is developed considering the geometry and vibration periods of the cap. The proposed mixed method is applied to a 4-pile experimental specimen for the modal and time history analyses. The results are shown good satisfactory when compared to the experimental data, or to the finite element solutions and other analytical solution in the literature. The method improves the calculation accuracy and efficiency and is a valuable reference for the seismic analysis and design of the deep-water elevated pile cap foundation.