30t轴重重载铁路简支梁桥－轨道系统地震响应研究

摘要

In order to study seismic responses of a multi-span heavy loaded railway simply-supported bridges-tracks system,the validated bridge-track interaction analysis method was used to establish the simulation model of interaction between heavy loaded railway simply-supported bridges and double ballast tracks considering pile-soil interaction,pier elastic-plastic deformation,sliding bearing friction and track nonlinear resistance.The study revealed the seismic response law of the heavy loaded railway simply-supported bridges and tracks system under the seismic uniform excitation and traveling wave effect.The influences of design parameters,such as,track segment length,simply-supported bridge amount,span length,track longitudinal resistance form and sliding bearing friction coefficient were discussed.The stress characteristics of the system under the coupling effects among temperature,train brake and earthquake were analyzed.The results showed that when the geological conditions are similar,simply-supported bridges can be reduced to 1 1 spans and 1 50 m is taken as the length of track segment on embankment;when the track resistance decreases,both collision and beam falling may occur between beams and between abutment and beam;under longitudinal uniform excitation,the track stress envelope shape is a “double-diamond”with its maximum value appearing near the abutment,and the dynamic instability may occur due to larger track-bridge relative displacements near beam gaps;under the traveling wave effect,the stress and deformation laws of the system change significantly,so it is necessary to consider the effect of traveling wave even for smaller span simply-supported bridges;temperature and train braking action further increase the possibility of dynamic instability of the system under earthquakes.%为研究多跨30 t 轴重重载铁路简支梁桥－轨道系统地震响应规律，采用经过验证的梁轨相互作用模拟方法，建立了考虑桩－土共同作用、桥墩弹塑性变形、滑动支座摩阻力、线路非线性阻力的多跨重载铁路简支梁桥与双线有砟轨道相互作用仿真模型，揭示了一致激励和行波效应下重载铁路简支梁桥－轨道系统地震响应规律，探讨了路基段钢轨长度、简支梁跨数、跨度、线路纵向阻力形式、滑动支座摩阻系数等设计参数的影响，分析了温度、列车制动和地震耦合作用下系统的受力特征。研究表明：当地形地质条件相差不大时，简支梁跨数可简化为11跨、路基段钢轨长度可取为150 m；线路阻力减小时，梁体间、梁体与桥台间可能出现碰撞现象甚至发生落梁；纵向一致激励下，钢轨应力包络图呈“双菱形”，其最大值出现在桥台附近，而梁缝附近梁轨相对位移较大，易发生动力失稳；行波效应下，系统受力和变形规律发生显著改变，即使对于跨度较小的简支梁桥，也应考虑行波效应的影响；温度和列车制动作用将进一步增大轨道结构在地震中发生动力失稳的可能性。