Influence of pier height on the safety of trains running on high-speed railway bridges during earthquakes

桥墩高度对地震下高速铁路桥上行车安全性影响研究

Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge system.In this paper,a experiment of a train running on a high-speed railway bridge is performed based on a dynamic experiment system,and the corresponding numerical model is established.The reliability of the numerical model is verified by experiments.Then,the experiment and numerical data are analyzed to reveal the pier height effects on the running safety of trains on bridges.The results show that when the pier height changes,the frequency of the bridge below the 30 m pier height changes greater;the increase of pier height causes the transverse fundamental frequency of the bridge close to that of the train,and the shaking angle and lateral displacement of the train are the largest for bridge with 50 m pier,which increases the risk of derailment;with the pier height increases from 8 m to 50 m,the derailment coefficient obtained by numerical simulations increases by 75% on average,and the spectral intensity obtained by experiments increases by 120% on average,two indicators exhibit logarithmic variation.

突发地震对高速铁路桥上行车安全构成显著威胁,而桥墩刚度是影响列车-轨道-桥梁系统震时动力响应的重要因素之一。现有研究主要采用数值仿真方法来评估桥墩高度对桥上行车安全性的影响,缺乏相应的试验验证。本研究基于四台阵振动台和1:10缩尺的列车-轨道-桥梁模型,考虑8、16、24、30、40和50 m共6种桥墩高度,开展了地震下高速铁路桥上行车安全性试验,建立并利用试验时的系统响应校验了列车-轨道-桥梁数值模型。本文分析试验中的结构响应与数值模拟结果,得到墩高对行车安全性的影响规律。结果表明,桥墩高度变化时,30 m墩高以下的桥梁频率变化更大,更容易使桥梁响应频率接近地震主频,降低行车安全性;墩高增加使桥梁横向一阶频率接近列车摇头频率,50 m墩高时列车摇头角和横向峰值位移最大,增加了脱轨风险;墩高从8 m增高到50 m,数值模拟所得的脱轨系数平均增大75%,行车试验所得的谱强度指标平均增大120%;两指标都表现出对数变化规律。本研究结论可为高铁桥梁桥墩设计提供参考和指导。