Narrow Results

This study develops the train sub-model by multibody dynamic theory and establishes the longitudinally connected ballastless track-bridge sub-model using finite element theory. The two sub-models are assembled into a joint simulation model of train–track–bridge system coupling dynamic (JSTTBS) through wheel–rail contact relationships. Then, the influence of interlayer connection failure and pier settlement on the dynamic index of train–track–bridge system is analyzed, the intrinsic topological relationship (ITR) between pier settlement amplitude and dynamic index considering interlayer connection failure is proved, and the pier settlement threshold is proposed. The results showed that the calculation results of JSTTBS considering the interlayer connection failure and pier settlement are in good agreement with the literature data, verifying the model’s accuracy. The void beneath the slab caused by the pier settlement aggravates the train dynamic index change. After considering the void beneath the slab, the maximum value of each dynamic index is about two times that without accounting for the void. The uneven settlement value of the pier derived from the ITR is within 22.47mm, which is in good agreement with the calculation result of the established JSTTBS of 23.08mm, indicating the reliability of the ITR to calculate the uneven settlement threshold of the pier.

Operation safety of high-speed trains is dependent on their vibration characteristics, which vary with bridge deformation. This paper studies the influence of bridge pier settlement and girder creep camber, which are two typical types of long-term bridge deformation, on the vibration of high-speed trains. To this end, an analytical approach is presented to link the bridge deformation with railway track deformation; the track deformation is used to analyze the vibration of the CRH2 high-speed train in China. The vibration analysis results are validated using the in-situ measurement data. The present study shows that bridge pier settlement greatly affects the vertical acceleration, derailment coefficient and wheel unloading rate of the high-speed train; incorporating bridge girder camber aggravates the vibration of the train–bridge system. The threshold of bridge pier settlement is suggested to be 11.1mm for trains moving at 350km/h with regard to the code-specified vibration limit. This study has significant implications for the design and operation of high-speed railways.

A nonlinear dynamic model of a train–bridge-longitudinal track coupling system considering the dynamic contact of the bridge–track interface (BTI) is established. Based on the previously established BTI contact characterization model and train–bridge coupling joint simulation model, the proposed model is verified from both static and dynamic perspectives. Accordingly, the dynamic displacement variation law of the bridge–track structure before, during and after the train passing through the side pier settlement area, the additional stress dynamic variation law and the interlayer connection dynamic variation law are analyzed. Moreover, the amplification effect of the wheel repeated “beating effect” on the dynamic contact force of “disengagement-closure-redisengagement” of the BTI void area is also analyzed. The results show that the accuracy of the proposed model can be verified from both static and dynamic perspectives. During the train passes through the settlement area, the dynamic deformation of track is the largest. Before and after the train passes through the settlement area, the dynamic deformation of track is basically the same. During the train passes through the settlement area, the BTI completes a dynamic contact process of “disengagement-closure-redisengagement”. The static effect of the side pier settlement on the dynamic bonding force of sliding layer is much larger than the dynamic effect of the train load. The dynamic effect of the train load is much larger than the static effect of the side pier settlement on the dynamic bonding force of the CA mortar and fasteners. The side pier settlement has a dynamic amplification effect on the train wheelset. Along the mileage direction, there are interface voids and contact areas in the dynamic bonding force of sliding layer and CA mortar, while there are no voids and contact areas in the dynamic bonding force of fasteners.