Mechanical Property Analysis On The Structure Of The Curve Segment Floating Slab Track

As one of the tracks with the best vibration absorption effect at present,the steel spring floating slab track structures are widely applied in subway projects in various large and medium-sized cities in China.As this structure can effectively reduce the vibration effect of the train,the influence on ground-surface conditions is reduced.In order to provide the best effects of vibration absorption and noise reduction to the tracks,it is necessary to make a mechanical property analysis on the tracks.With a section of steel spring floating slab track in Hangzhou subway line 1 as the research background of this paper,the finite element software ANSYS is adopted for selecting appropriate elements and parameters so as to establish four kinds of steel spring floating slab track models,namely,curve segment steel spring floating slab track,linear segment steel spring floating slab track,ordinary monolithic track-bed and track-tunnel-soil body finite element models.The research on factors influencing the inherent frequency of the floating slab track system,vibration transmission property of the floating slab track and its impact on ground-surface conditions is focused in this paper.The specific contents are as follows:In the first part,the floating slab finite element model is established to research the deformation of the track as well as the distribution of stresses when the static load is applied and,at the same time,discuss the influence rule of various parameters;displacements among slabs with or without shear hinges are also analyzed in this part.The research shows that steel spring stiffness has a great influence on the displacement and stress distribution of the system and that the shear hinges can effectively avoid "slab staggering" among slabs.In the second part,the inherent frequency and formation of the floating slab track system are obtained through model analysis specific to the established models;and then the influence of individual parameters on the inherent frequency of the system is discussed to give the reasonable value range or recommendation.The research shows that the steel spring stiffness,the steel spring space,the density of the floating slab and the length of the floating slab are important parameters which exert influences on the inherent frequency of the system.In the third part,the vibration transmission property of the track is analyzed by harmonic response analysis using the established models in order to analyze the differences between the linear segment tracks and the curve segment tracks at first and then analyze individual response rules under different segments;and then,the influences of various parameters on the system vibration isolation and excitation force attenuation are researched considering the actual situations to give reasonable parameter selections or recommendations.The research shows that the steel spring stiffness,the steel spring space and the steel spring damping are important parameters which impact the vibration isolation effect of the system.In the fourth part,the advantages in vibration absorption of the floating slab track are obtained after the comparison between the floating slab track and common slabs,by simulating the influence on ground surface vibration when the loaded train runs through the track using the track-tunnel-soil body finite element model;finally,the attenuation law of track's vertical vibration and ground-surface's horizontal vibration with different parameters is analyzed to give reasonable parameter selection ranges and recommendations in combination with knowledge given in the previous chapters.The research shows that the steel spring stiffness,the steel spring damping,the steel spring space and the embedment depth of the track are important parameters which exert influences on the vibration attenuation.