Running safety and seismic optimization of a fault-crossing simply-supported girder bridge for high-speed railways based on a train-track-bridge coupling system

基于车-线-桥耦合系统的跨断层高铁简支梁桥地震下行车安全及抗震优化研究

Bridges crossing active faults are more likely to suffer serious damage or even collapse due to the wreck capabilities of near-fault pulses and surface ruptures under earthquakes.Taking a high-speed railway simply-supported girder bridge with eight spans crossing an active strike-slip fault as the research object,a refined coupling dynamic model of the high-speed train-CRTS III slab ballastless track-bridge system was established based on ABAQUS.The rationality of the established model was thoroughly discussed.The horizontal ground motions in a fault rupture zone were simulated and transient dynamic analyses of the high-speed train-track-bridge coupling system under 3-dimensional seismic excitations were subsequently performed.The safe running speed limits of a high-speed train under different earthquake levels(frequent occurrence,design and rare occurrence)were assessed based on wheel-rail dynamic(lateral wheel-rail force,derailment coefficient and wheel-load reduction rate)and rail deformation(rail dislocation,parallel turning angle and turning angle)indicators.Parameter optimization was then investigated in terms of the rail fastener stiffness and isolation layer friction coefficient.Results of the wheel-rail dynamic indicators demonstrate the safe running speed limits for the high-speed train to be approximately 200 km/h and 80 km/h under frequent and design earthquakes,while the train is unable to run safely under rare earthquakes.In addition,the rail deformations under frequent,design and rare earthquakes meet the safe running requirements of the high-speed train for the speeds of 250,100 and 50 km/h,respectively.The speed limits determined for the wheel-rail dynamic indicators are lower due to the complex coupling effect of the train-track-bridge system under track irregularity.The running safety of the train was improved by increasing the fastener stiffness and isolation layer friction coefficient.At the rail fastener lateral stiffness of 60 kN/mm and isolation layer friction coefficients of 0.9 and 0.8,respectively,the safe running speed limits of the high-speed train increased to 250 km/h and 100 km/h under frequent and design earthquakes,respectively.

由于地震时断层地表破裂和近断层脉冲的强破坏能力,跨越活动断层桥梁更易遭受严重损伤甚至倒塌。以跨越某走滑型活动断层的八跨高铁简支梁桥为对象,基于ABAQUS有限元平台建立了高速列车-CRTS III型板式无砟轨道-桥梁的精细化耦合系统动力学模型,并对其合理性进行了讨论。模拟断层区水平向地震动,开展了三向地震下车-线-桥耦合系统的瞬态动力分析。基于列车横向轮轨力、脱轨系数、轮重减载率等轮轨动力指标,以及钢轨错位、平行转角、折转角等钢轨变形指标,探讨了多遇、设计、罕遇地震水平下高铁列车安全行车的速度限值,并从钢轨扣件刚度和轨道隔离层摩擦因数角度讨论了轨道结构的参数优化。研究结果表明,从列车轮轨响应角度,多遇和设计地震下,列车安全行车的速度限值分别约为200 km/h和80 km/h,罕遇地震下则无法保障安全行车;从钢轨变形角度,多遇、设计和罕遇地震下,分别可满足列车以250 km/h、100 km/h和50 km/h速度行车的变形要求。从列车轮轨响应角度得出的速度限值更小,这是由于考虑了线路不平顺条件下车-线-桥系统的复杂耦合效应。列车行车安全性随扣件刚度和隔离层摩擦因数的提高有所提升,当扣件横向刚度为60 kN/mm,隔离层摩擦因数分别调整为0.9和0.8时,多遇和设计地震下的行车速度限值可分别提高到250 km/h和100 km/h。