铁路简支梁桥基础刚度的静动力影响研究

Study of Static and Dynamic Influences of Foundation Stiffness of Railway Simply-Supported Beam Bridge

为考察基础布置形式对桥梁静、动力性能的影响,设计一座55跨不同墩高的双线简支梁桥,采用有限元法分析对比2种基础自身刚度差异和基础-墩组合刚度差异,及桥梁结构动力特性和车-桥耦合振动特性。研究结果表明,考虑基础刚度后所得基础-墩身组合刚度较墩身刚度下降明显,横桥向刚度下降尤其显著;基础刚度对桥梁结构的自振特性影响有限;车辆通过桥梁时,车辆动力响应对桩基础布置形式的差异不敏感;基础刚度对桥墩顺桥向振动幅值影响较小,对桥墩横桥向振动幅值影响较为明显。在高速铁路上,应当考虑基础刚度对桥梁横向振动的影响。

To investigate the influence of different foundation layout on the static and dynamic behavior of bridge, a 55-span double-track railway simply-supported beam bridge with different pier height is designed and the finite element method is used to analyze and compare the differences of the foundationls own stiffness and the foundation-pier combination stiffness of two types of foundations, the structural dynamic characteristic of the bridge and the vehicle-bridge coupling vibration characteristic. The results of the analysis and comparison indicate that after the foundation stiffness is considered, the obtained foundation-pier combination stiffness decreases significantly in comparison to the pier shaft stiffness and the decrease of the stiffness transverse to the bridge is particularly significant. The influence of the foundation stiffness on the natural vibration characteristic of the bridge structure is limited. When vehicles pass through the bridge, the dynamic response of the vehicles is not sensitive to the differences of the pile foundation layout. The influence of the foundation stiffness on the vibration amplitude values of the piers along the bridge is little, however, the influence on the vibration amplitude values of the piers transverse to the bridge is significant. For the bridges on high-speed railway, the influence of the foundation stiffness on the vibration transverse to the bridge should be well considered.