多灾害作用下特大桥梁深水基础动力稳定性分析

Dynamic Stability of Deep Water Foundation of Extra-Large Bridge Under Multiple Disasters

以拟建的琼州海峡大桥深水基础为研究对象,考虑地震力、船撞力、波浪力等多种灾害因素,采用有限元动力分析法对深水基础位移响应进行分析,探讨其动力响应特性.结果表明:深水基础在地震力作用下基本为同向运动,并发生较大的水平位移,100年超越概率4%(E2水准)时位移最大达24.4cm.船撞力作用下,水平位移达15.1cm;波浪力作用下,水平位移达10.8cm;群桩在动荷载作用下响应复杂,由于土体的约束以及上部大刚度沉井的惯性力作用,桩身及上部沉井相对位移较大,导致桩头部位发生明显的应力集中.计算结果可为今后特大桥梁深水基础,尤其是为琼州海峡大桥深水基础的设计提供参考.

Taking the deep water foundation of Qiongzhou Strait Bridge as the research object, and aimed at the issue of dynamic stability of deep water foundation of extra large bridge, the disastrous factors such as seismic load, ship impact load and wave forces were considered. Based on the dynamic FEM, the charac- teristics of dynamic response of the deep water foundation, the displacement response under the actions of multiple disasters were explored and analyzed. The caisson of the foundation represents without any phase difference basically under seismic force, and maximum displacement reaches 24.4 cm. The horizontal dis- placement reaches 15.1 em under ship impact force, and 10.8 cm under wave force. The pile group shows complex response under dynamic load. Due to the constraints of soil and function of inertial force of the caisson, the relative displacement between the pile body and caisson is large, which leads to obvious stress concentration at pile head. The results can provide references for the design and construction of deep water foundation, especially for Qiongzhou Strait Bridge.