桥墩不均匀沉降对高速列车运行安全影响研究

Influence of uneven settlement of bridge piers on running safety of high-speed trains

针对运营阶段列车循环加载导致软土地基桥梁产生附加不均匀沉降威胁行车安全性问题,分别建立车辆-桥梁动力相互作用模型、桩基础-地基沉降模型。将用动力模型获得列车过桥时支反力时程作为外部激励,利用沉降模型研究列车荷载作用下桩基础的累积沉降规律;将由桥墩沉降产生的附加线形变化叠加到原始轨道不平顺中,考虑由其引起的竖向类离心力影响,用动力模型研究桥墩不均匀沉降对列车行车安全影响。以德国ICE3高速列车及三跨32 m简支梁桥为研究对象进行实例分析,结果表明,软土累积沉降主要发生在桩底约10 m厚土层范围内;相邻桥墩沉降引起的桥梁相对上拱对行车安全更不利。

The piles of bridge built on soft clay foundation produce additional settlement due to cyclic loading of moving trains,which affects the operation safety of the train.A dynamic model of vehicle-bridge system and a settlement model of pile foundation-soil system were established.The reaction force induced by the moving vehicle was got by using the dynamic model which was then taken as the external excitation of the settlement model to study the train-induced cumulative settlement. The additional track irregularity induced by settlement pier was overlaid on original track irregularity,and the influence of the vertical centrifugal force induced by pier settlement,on the running safety of train was considered in virtue of the dynamic model.As a practical example,the German ICE3 train running on a 32 m three-span simple-supported beam was analysed.The results show that the most cumulative settlement occurs in the range of 10 m below the pile bottom.The relative camber of the bridge induced by adjacent pile settlement is more dangerous to running safety of the train,because the train bears vertical centrifugal force in the direction opposite to the settlement direction,when it runs on the bridge with camber.