Structural Design And Impact Characteristics Of Embedded Track System Of High-speed Railway

With the increasing demand of urban rail transit and the development of rail vibration and noise reduction technology,embedded rail has been paid more attention because of its great advantages in vibration and noise reduction.At present,embedded track is more used in trams and metro lines,but the research and report on embedded track for high-speed rail is still relatively lacking.Therefore,this thesis analyzes the structure of embedded track system based on the existing high-speed rail use environment and relevant specifications.The main work of this thesis is as follows:(1)Based on the investigation of embedded track related data,the supporting stiffness range of high-speed embedded track system is determined in this thesis.(2)By establishing the structure model of embedded track system,the parameters in the embedded track slot are optimized from two aspects: the stiffness of embedded track system and the loading state of components in the slot,finally,the parameters of the components in the embedded track slot are determined as follows: The elastic modulus of polymer material is 15 MPa,the elastic modulus of noise reduction block is 20 MPa,the elastic modulus of the under rail base plate is 2.4 MPa,the lateral stiffness of the floating rail fastener is 50 k N/mm,the longitudinal spacing of floating rail fastener is 1000 mm.(3)The stiffness of the embedded track specimen is tested,the test results show that the vertical dynamic stiffness of embedded track specimen decreases with the increase of preload,with the increase of loading frequency,the increase trend is first fast and then slow,the equivalent viscous damping ratio increases linearly with the increase of preload;The correctness of the model is verified by the experimental results,according to the stiffness damping of different frequencies and preloads,the damping constitutive parameters of the embedded track rolling contact model are also determined.(4)By comparing the cost of the type Ⅰ,type Ⅱ,and type Ⅲ track slab scheme formulated in this paper and the limit ability of the limit mechanism,the type Ⅲ track slab scheme is finally determined as the optimal scheme;According to the maximum longitudinal and transverse bending moments of type III embedded track slab,the reinforcement is checked,compared with the reinforcement results of the existing track slab,the reinforcement ratio is reduced by 26.5% at most.(5)The three-dimensional transient wheel-rail rolling contact model is used to compare and analyze the wheel-rail dynamic response under smooth track conditions and welding irregularities.The results show that the initial wheel-rail vertical force fluctuates greatly due to factors such as wheel inertia at the initial time of the explicit power program calculation.This impact can be eliminated by applying the corresponding initial speed to the wheel in the implicit calculation;The conventional fastener-type track and the embedded track have similar performances in the wheel-rail vertical force and the sprung mass vertical acceleration under smooth conditions,but due to the continuous support of the embedded track,the vertical force of the wheel rail is more stable than that of the fastener rail;As the operating speed increases,the maximum wheel-rail vertical force of the embedded track with welding irregularities,the reduction of the wheel-rail vertical force,the maximum vertical acceleration of the sprung mass,and the maximum vertical displacement of the rail gradually increase.After the welding irregularities are added,the wheel-rail vertical forces of the two rails show the same trend.Compared with the fastener-type rail,the dynamic performance of the embedded rail is better than that of the fastener-type rail.Especially in terms of the reduction of the wheel-rail vertical force,the vertical acceleration of the sprung mass,the vertical acceleration of the axle and the rail,etc,improve the safety and comfort of the train to a certain extent.