考虑桩土相互作用的车-轨-桥系统地震响应分析

Seismic Responses Analysis of Train-Track-Bridge System Considering Pile-Soil Interaction

弄清桩土相互作用对车桥系统地震响应的影响对于研究地震引起的高速铁路桥上列车行车安全问题十分必要.基于列车-轨道-桥梁耦合振动理论,采用Winkler地基梁模拟群桩基础并通过m法计算弹簧参数,建立了地震作用下的列车-轨道-桥梁-群桩耦合振动模型,并编制了仿真分析程序.以某(88+168+88)m预应力混凝土连续刚构桥为例,分别建立了考虑桩土相互作用的群桩基础模型以及作为对比的刚性基础模型和弹性基础模型,通过输入3条典型地震波,计算对比了3种模型的耦合振动响应,研究了桩土相互作用的影响.结果表明:地震作用下桩土相互作用对桥梁、轨道和列车子系统动力响应的影响横向大于竖向,且对桥梁、轨道子系统动力响应的影响大于列车子系统;对于本文的计算条件,不考虑桩土相互作用会使桥梁、轨道和列车子系统的动力响应偏小,其中列车的脱轨系数、轮重减载率和轮轴横向力平均值分别偏小5.8%、8.6%和9.0%;桩土相互作用对列车行车安全性指标的影响不会随车速的变化而变化.本文的研究成果可为震区高速铁路桥梁的抗震设计提供参考.

Understanding the influence of pile-soil interaction on seismic responses of a train-bridge system is necessary for studying the safety of trains running over high-speed railway bridges under earthquake.Based on the train-track-bridge coupled vibration theory,the Winkler foundation beam is used to simulate the pile group foundation and spring parameters are calculated by m method.A complete train-track-bridge-pile group coupled vibration model with seismic excitations is established,and a simulation analysis program is developed.Taking a(88+168+88)m prestressed concrete continuous rigid frame bridge as an example,a pile group foundation model considering pile-soil interaction,a rigid foundation model and an elastic foundation model are established respectively,and the last two models are used for comparison with the first one.By inputting three typical seismic waves,the coupled vibration responses of the three models are calculated and compared,and the pile-soil interaction is studied.The results show that the influence of pile-soil interaction on the lateral dynamic responses of the bridge,track and train subsystems under earthquake is greater than that on the vertical one,and the influence on the dynamic responses of the bridge and track subsystems is greater than that of the train subsystem.For the calculation conditions of this paper,the dynamic responses of bridge,track and train subsystems will be smaller if pile-soil interaction is not considered;specifically,the derailment coefficient,wheel load reduction rate and wheel-axle lateral force of the train are 5.8%,8.6%and 9.0%smaller,respectively.Besides,the influence of pile-soil interaction on the safety index of the train will not change with the train speed.The obtained results can provide reference for the seismic design of high-speed railway bridges in earthquake areas.