波浪荷载作用下跨海桥梁群桩基础方案研究

Study on Group Pile Foundation Scheme of Sea-crossing Bridge Under Wave Loading

针对波浪荷载作用下跨海桥梁群桩基础的设计问题,以平潭海峡公铁两用跨海大桥主桥为工程背景进行了群桩基础方案的数值模拟分析。首先,建立全桥有限元模型计算上部结构对基础的作用力;其次,建立了4种不同群桩基础方案的有限元模型,分别采用Morison方程和绕射理论计算桩基、承台和围堰受到的波浪荷载,并分析了各群桩基础方案在波浪荷载作用下的受力性能;最后,通过比较不同设计方案的工程量及施工可行性,给出了较优的设计方案。研究结果表明:波浪荷载对跨海桥梁围堰设计及施工的影响尤为显著;承台高程提高后可以有效减小围堰承受的波浪荷载,降低施工难度与风险;承台高程提高后采用增大桩径的方法,可以有效改善基础受力性能,减少工程量,控制工程投资。

Aiming at the design problem of group pile foundation of sea-crossing bridge under wave loading,the numerical simulation analysis of group pile foundation scheme of the main bridge of Pingtan strait rail-cum-road sea-crossing bridge was carried out under the engineering background.Firstly,the f inite element model of the whole bridge was established to calculate the action of the superstructure on the foundation.Secondly,the f inite element models of four different group pile foundation schemes were established.The wave loads on pile foundation,cap and cofferdam were calculated by Morison equation and diffraction theory respectively.The mechanical properties of group pile foundation schemes under wave loading were analyzed.Finally,an optimal scheme was given according to the comparsion on the the engineering quantity and construction feasibility of different design schemes of the group pile foundation.The results show that the inf luence of wave loads on the design and construction of cofferdam for sea-crossing bridges is particularly signif icant .The wave loads on cofferdam can be effectively reduced and the construction diff iculty and risk can be reduced with the increase of the elevation of cap.On the basis of increasing the elevation of cap,the method of increasing the diameter of the pile can effectively improve the mechanical properties of the foundation,reduce the amount of work and control the investment of the project.