Research On Service Performance And Health Management Method Of CWR On Cable Stayed Bridges With Thousand-Meter-Scale Main Span

The bridge engineering in the substructure of high-speed railway in China is developing rapidly.In the current and future high-speed railway construction,super long span cable-stayed bridge will be extended to cross sea railway and Sichuan-Tibet railway.Laying continuous welded rail(CWR)on super long span cable-stayed bridge is faced with many problems,such as more special interaction between beam and rail,more changeable spatial attitude of structure,more difficult to master service state and so on.In the existing research,the research on the service performance and health management of CWR on cable-stayed bridge with thousand-meter-scale main span is relatively scarce.It is difficult to explain and solve the problems of sleeper cracking,track geometry overrun and uneven longitudinal force distribution in field operation.It is very important to carry out the research on the static and dynamic characteristics and long-term service performance of CWR on cable-stayed bridge with thousand-meter-scale main span,and put forward the health management method of track structure and its infrastructure system.In view of the background,based on the principle of beam rail interaction and the theory of vehicle track coupling dynamics,this paper establishes a spatial coupling static and dynamic analysis model of CWR on high-speed railway kilometer class main span cable-stayed bridge by using finite element method and multi-body dynamics method,which can take into account the influence of front and back load steps and the whole loading history.This paper analyzes the basic mechanical characteristics and long-term service performance of CWR on bridge under the action of temperature and train load,studies the structural dynamic characteristics of beam end area and main beam mid span area,and tentatively puts forward the health management method of CWR on cable-stayed bridge.The main work and achievements of this paper are as follows:(1)The expansion force of CWR is mainly affected by the temperature change of the main beam,and the longitudinal resistance degradation of track in expansion zone will reduce the longitudinal force of rail and increase the longitudinal relative displacement of beam rail.The length of train load has a great influence on the longitudinal stress and deformation of CWR,and the highway load has an increase of 20% to 30%.Under the braking force,the longitudinal movement of the main girder is mainly limited by the main tower and stay cables,and the force of the main tower is much greater than that of the side span piers.The setting of the Rail Expansion Joints(REJ)can reduce the stress of the rail at the end of the main beam,coordinate the deformation of the rail and the bridge,and reduce the longitudinal stress of the pier and the main tower.In practical engineering application,it can be flexibly compared and selected according to the field situation.With the growth of the line operation period,the sleeper on the side with excessive displacement is easy to be cracked at the stress concentration of fasteners,supporting beam bolts of sleeper lifting device,etc.,which should be paid attention to during the line operation period.(2)In the process of temperature ’ loading-unloading-reverse loading ’,the line longitudinal resistance enters the plastic state,and there is still residual longitudinal resistance after temperature unloading.Under different loading histories,there is a great difference between rail residual force and CWR residual deformation when temperature load is zero.When the train is under the action of bending and braking in the range of the main bridge,the transient analysis method of continuous load step considering the hysteresis characteristics of longitudinal resistance of the line and the speed of the train can not only obtain the envelope value of the structural stress and deformation of the whole course of the train action,but also take the influence of the early loading into account,which is more in line with the actual situation.When the multi-load coupling effect occurs,the influence of the stress deformation of the previous structure on the change of the next structural state should be taken into account.Therefore,the load step method considering the loading history should be used to couple the multi-load conditions,so that the calculation results are more in line with the actual situation.(3)The vehicle-track-bridge dynamic response in the beam end area is more intense.The vibration of the REJ set on the side span is more obvious than that set on the main beam,and the farther the position is from the beam end,the more intense the vibration is.Under the long-term operation condition,the dynamic indexes of the REJ area have significant effects.The vertical dynamic indexes of the vehicle-track-bridge in the mid-span area of the main girder meet the requirements of the specification.With the increase of the vehicle speed,each index increases linearly.With the deterioration of the line operation state,if the train is still running at the designed speed,the safety margin may not be sufficient to meet the requirements.(4)The overall scheme of railway infrastructure detection and monitoring based on the integration of "air sky vehicle ground" is proposed,which integrates multi monitoring technology means fusion,multi-source heterogeneous detection and monitoring data fusion and accumulation technology,and realizes multi-element integrated long-term digital monitoring and early warning.Based on the integration application of BIM and GIS technology,the data fusion method and dynamic display scheme are proposed.The CWR system on long cable-stayed bridge of high-speed railway focuses on the end of the main beam and the mid-span of the main beam.The monitoring indicators are analyzed and the monitoring scheme is proposed.The process of track structure state prediction is illustrated by an example.The reasonable prediction method can realize the sensing of structure service state in advance,reduce the cost of system hardware and improve the accuracy of the system.There are 185 figures,15 tables and 114 references.