Study On The Vibration Reduction Performance Of Elastic Material Of Track Structure For The Tramcar

In recent years,for solving the travel problem of urban residents and promoting the construction of urban ecological civilization,the modern tram with low carbon environmental protection and larger capacity have been developing rapidly.However,since tramcar passing through the urban densely populated areas,the environmental vibration caused by the running of tram has aroused widespread concern.So as to reduce the impact of environmental vibration on residents and buildings along the track,the polymer elastomer material is utilized to coat the rail web and soil is covered to plant greensward under the track in order to achieve the effect of vibration reduction on the track structure of tram ground line.The theoretical analysis shows that the elastic material has effect on vibration and noise reduction,but there is still unclear how much effect the material can work in practical engineering application.Therefore,based on the contract project,named " Measurement and Evaluation of Vibration and Noise in the Test Section of New Tramways around the Island in Haizhu District,Guangzhou City ",the performance of elastic material coated the rail web to reduce ambient vibration is discussed,the main contents are as follows:(1)Firstly,according to the results of time domain,spectrum and vibration level analysis,the difference of ambient vibration caused by the running of tram when it carries passengers in normal operation or is no-load.Secondly,the paper discusses influence of different geological conditions and different foundation treatment methods to the law of ground environmental vibration propagation.The results show that when explores the vibration absorption performance of different elastic materials,Whether the tram is manned or not has no obvious effect on the analysis results,whereas different geological conditions and different ground treatment methods have great influence on the ground environment vibration induced by tram operation.(2)Field measurement environmental vibration data of different operating conditions,is analyzed to compare the vibration absorption effects of elastic materials with different crosssection shapes.According to the results,the effect of elastic coated materials with different cross-section shapes on vibration reduction is limited,which only affects the ambient vibration within 8 m from the central line of the track,and has a better effect on the low frequency vibration.When the train speeds up,the inhibitory action of elastic material to the raise of environmental vibration is reflected within 8 m from the central line of the track,but when the distance is more than 16 m,the vibration absorption of different elastic cladding materials is inconspicuous.(3)Based on the FEM software ANSYS,the 3D track structure–foundation models of different operating conditions are studied.By setting the model parameters reasonably and analyzing the simulation methods of different train moving loads,the analog calculation results of vibration reduction effect of different elastic cladding materials in numerical simulation environment is discussed and compared with measured values.The results show that the simulated results are in good agreement with the measured values,which validates that the materials can only reduce the vibration in the near-end of the track and have more influence on the low frequency vibration.Meanwhile,the cross-section shape of the material has an effect on the propagation of environmental vibration,and it is confirmed that different geological conditions have great influence on the propagation of ground environmental vibration.(4)Based on the 3D track structure–foundation models with elastic coated material,the influence of elastic coated material parameters(including elastic modulus and damping loss factor)and other factors on reducing the environmental vibration induced by tram are analyzed.The results show that by changing the material parameters can only affect the vibration of track structure,but has no influence on the vibration disseminating to the outside of the track.It is contributed to reduce ambient vibration that coats elastic material on the rail web and cover the earth above the track.Meanwhile,setting up a drain with a reasonable depth at a certain distance from the track can effectively reduce the environmental vibration.