Research On Dynamic Response Of Subway Track Structure With Floating Slab And Analysis Of Parameter Influence

In recent years,with the rapid growth of urban population in China,the problem of urban traffic congestion has become increasingly severe.The emergence of urban rail transit has solved this problem well.As a dominating modality of urban rail transit,subway system has developed into the best choice for urban population travel because of its high capacity,high safety and efficiency.However,since the subway develops rapidly in China,the dynamic problem of vehicle interaction with track structure is becoming more and more grievous.Due to the dynamic issues between the vehicle and track,which directly affect the safety of the vehicle and track structure during operation,and the track structure serving as the foundation for driving,the research on its dynamic response,vibration reduction,and vibration isolation has certain theoretical value and social significance.In this article,the floating plate track structure is chosen as the research target since it is usually applied in subway track structure system construction and it has good vibration damping capacity.Firstly,based on Winkler’s elastic foundation beam theory,the floating slab track is simplified into a double-layer Euler-Bernoulli elastic foundation beam model,and the vibration differential equation of the double-layer beam is built.The differential equation is solved by combining the initial parameter method and modal superposition method.The dynamic response equations(including dynamic displacement,dynamic bending moment and dynamic stress equations)of the calculation model under moving resonant load can be obtained.Subsequently,on the basis of the realistic operating mode,a finite element analytical model setting of the track structure system has been built.And then,to demonstrate the dependability of the theoretical calculation,the obtained results are compared with the theoretical calculation.Combined with the resonance conditions,the dynamic response of the orbital structure during the resonance process is solved,and compared with the image without resonance,so as to illustrate the harm of resonance.Then,using the univariate variational method,the dynamic response of each component and load motion parameter of the floating plate track structure system to the track structure is analyzed.Since the frequency of the external load is equivalent to the natural frequency of the track structure system,the phenomenon of resonance will take place.Thereupon,the vibration of the track structure will be very violent.In order to avoid resonance phenomenon and improve the vibration isolation ability of track structure,it can be seen from the transmission ratio design curve of the system that reducing the natural frequency of track structure can achieve the purpose of improving the vibration isolation ability.Using the finite element model of track structure system which has been established in the above study,the first 8 natural frequencies and vibration modes of track structure system can be extracted.Then,the influence of different orbital parameters on natural frequencies of track structure is studied,and the way of improvement of the vibration isolation ability of the track structure is discussed.The results show that adjusting the density,geometric parameters,fastener stiffness and support stiffness of the floating plate in the track structure has a good effect on reducing the deformation of the track under load and enhancing the vibration isolation capacity of the whole track structure system.To sum up,research results can provide floating slab track structure system with design basis.