跨海大桥小尺度下部结构非线性波浪荷载分析

为研究跨海大桥桩基、桥墩等小尺度下部结构波浪荷载的非线性特性,以平潭海峡大桥N01号桥墩为例,采用不可压缩流体的N-S方程以及VOF自由液面追踪法,通过FLUENT实现非线性波的二维数值模拟,进而分析非线性波浪速度场和波面变化的特点,并通过Morison方程对比桥墩和单桩在线性波和非线性波下波浪荷载的差异,同时,为进一步研究浅水区非线性波浪特点,对不同直径下桥墩非线性波浪荷载的影响进行研究。研究表明:对于深水区的单桩,非线性波的非线性作用不明显;对于浅水区的桥墩,非线性波与线性波波浪力差异有14%,非线性作用较为显著;随着直径的增加,桥墩发生非线性波浪力峰值滞后现象;在跨海大桥设计中,波浪荷载的非线性应予以重视。

Analysis of Nonlinear Wave Load on Small Size Substructure of Cross-sea Bridge

To study the nonlinear characteristics of wave loads on such small size substructure as pile foundation and pier of the cross-sea bridge,N0. 1 pier of Pingtan Bridge is taken for reference. Based on the N-S equation of incompressible fluid and VOF free surface tracking method, two-dimensional numerical simulation of nonlinear wave is conducted with FLUENT software to analyze the characteristics of velocity field and wave surface variations of nonlinear wave. The differencesbetween linear and nonlinear wave loads on the single pile and the pier are compared with Morison equation. In order to further study the characteristics of nonlinear wave in shallow water,the influences of the nonlinear wave loads of piers of different diameters are investigated. The results of the study show that the nonlinear effect of the nonlinear wave is not obvious on the single pile in deep water,and the difference between linear and nonlinear wave loads is 14% with significant nonlinear effect on the pier.With the increase of diameter,hysteresis of peak nonlinear wave load occurs. The nonlinear wave load should be addressed in the design of the cross-sea bridge.