Study On Floating Slab Track Upon Vibration-noise Controls In Viaduct Rail Transit System

The vibration in urban rail transit system is drawing more and more attention in recent years. Urban rail transit system, which has brought us with great convenience, also causes many problems such as vibration and noise inevitably. This thesis describes some means and measures of tracks controlling vibration and noise in the viaduct rail transit system. Emphasis is laid on floating slab track (FST), which is a mass-spring vibration isolation system and the best vibration-decreasing measure in rail transit system so far.This thesis researches on the vertically vibration of vehicle-track-bridge environment, makes use of vehicle dynamics, track dynamics, bridge dynamics, mode analysis theory, track-bridge dynamic finite element method and other based theories, takes vehicle, track, bridge environment as a whole vibration system connected by wheel-track relationship and track-bridge relationship. Dynamic traits of FST, the property of vibration-noise controls of FST, dynamic response of bridge system and vibration influence on environment are on target.In this thesis, a four-axle rolling dynamic model of metro vehicle is accepted, rails are modeled as Euler beams laid on elasticity supports, slabs are modeled as rectangle plates laid on elastic foundation, sleepers, blocks and discrete ballast blocks are modeled as rigid bodies. Meanwhile, based on the Hamilton principle of the discrete dynamical system, the motion equations of the bridge are established by finite element method; the element mass matrices and element stiffness matrices of spatial bar element, spatial beam element and plate element are presented; the damp matrices and eigenvalue of the bridge structure are also briefly discussed in this paper.In order to understand the key parameter, which influence the efficiency of floating slab track vibration isolation and provide theoretical support for simulation, we analyze the vibration isolation principle of floating slab track .This thesis analyzes the influence of track dynamics index by different track dynamic parameters and obtains the time domain curve of wheel-rail force and support force in the running process of metro. Based on an analysis soft ANSYS, vibration frequency and mode shape of different FST structures and bridges is analyzed, a coupling dynamic finite element modal of track-bridge system is set up. Then, acceleration and displacement of bridge are acquired. Field tests of vibration response of metro lines in different track structures are carried on to be compared with the results of analysis.