Research On Dynamic Performance Of Prefabricated Sleeper Slab Ballastless Track

Urban rail transit undertakes the transport function of the city,which can effectively alleviate the problem of urban traffic congestion,optimize the layout of urban structure,and promote social progress and economic development.In recent years,China’s urban rail transit has achieved explosive development.The number of cities with rail transit has continued to increase,and the number of subways under construction and operation has continued to increase.However,the traditional ballastless track type of urban rail transit is a cast-in-place monolithic track bed structure.The concrete pouring workload during on-site construction is relatively large,the construction period is long,and the construction quality is greatly affected by the operating quality of the operators.The prefabricated track structure can realize standardized design,modular production,and assembly construction,which can improve the construction quality of track engineering,shorten the construction period of rail transit,and has greater promotion and application value.China’s urban rail transit prefabricated track structure is still in the early stage of research and development,and it is urgent to carry out systematic research from multiple dimensions such as theory,design and application.This thesis takes the prefabricated sleeper ballastless track structure as the research object,analyzes the dynamic characteristics and structural parameters of the non-vibration damping type and the vibration damping type track structure,and carries out the fatigue test research of the two track structures at the same time.The main research work of the thesis includes:(1)The development status of urban rail transit is sorted out,the characteristics of common subway ballastless track structures are summarized,and the composition,characteristics and application prospects of prefabricated sleeper slab ballastless track structures are introduced.The research methods on track structure dynamics at home and abroad are sorted out from two aspects: theoretical research and experimental research.(2)Based on the vehicle-track coupling dynamics theory,the vertical coupling dynamics model of metro vehicle-precast sleeper slab ballastless track was compiled through the secondary development language of ANSYS.The wheel-rail coupling dynamics model and the reliability of the finite element model of the track structure were verified by calculation examples and experimental research results respectively.(3)Modal analysis,harmonic response analysis and vehicle-track coupling dynamics analysis are carried out on the non-vibration-damped track and the vibration-damped track.The relationship between the natural frequency and mode shape of the two track structures,and the response value of the track structure to the frequency is analyzed.The simulation analyzes the dynamic interaction between the vehicle and the track structure in the actual driving process and the influence of the driving speed on the dynamic response of the vehicle and the track structure.(4)The four parameters of the prefabricated sleeper slab ballastless track,the stiffness of the damping pad,the laying form of the damping pad,the thickness of the track slab,and the longitudinal connection length of the track slab are simulated and analyzed.Each parameter is analyzed from the vehicle running performance,the dynamic response of the track structure,and the track Vibration damping performance is analyzed in three aspects and its influence law is provided to provide references for the optimization of track structure parameters.(5)Relying on the full-size precast sleeper slab ballastless track structure test platform built by the laboratory,static load tests and fatigue tests are carried out.The results show that the strength and stiffness of the precast sleeper slab ballastless track meet the load-bearing requirements and have good fatigue resistance.