Research On Low Frequency Vibration Control Of Floating Slab Track Based On Tuned Viscous Mass Damper

With the rapid development of urban rail transit,environmental vibration and noise problems caused by train operation have become increasingly prominent.The existing research results show that the floating slab track(FST)has the best vibration isolation effect among the current vibration isolation structures of urban rail transit.FST can isolate medium and high frequency vibration well,but it has poor effect on low frequency vibration.The low frequency vibration is introduced into the soil through the track and tunnel structure,which will stimulate the vibration of nearby buildings,interfere with the life and work of residents,accelerate the damage of important ancient buildings,and affect the implementation of difficult operations and the use of precision instruments.Therefore,the research on low frequency vibration control of FST has important theoretical significance and engineering application value.In this thesis,the tuned viscous mass damper(TVMD)is applied to low frequency vibration isolation of FST structure,and the vertical coupling dynamic model of vehicle and FST isolated by TVMD is established.Based on the dynamic model and simulation method,the non-linear vibration response characteristics of FST supported by TVMD were investigated,and compared with the traditional steel-spring FST,the influence rule of TVMD system on the vibration reduction performance of the rail is verified.The influence of different parameter changes on the vibration isolation performance and parameter optimization design are discussed,which provides a reference for the application design of TVMD system in the field of track vibration reduction.Firstly,based on the fixed-point theory and equivalent linearization method,this thesis introduces the optimization design method of TVMD system parameters for single degree of freedom structure under the condition of damping and undamped,and gives the calculation formula of the optimum damping ratio,stiffness ratio and inertia mass ratio.Based on the principle of vehicle-track coupling dynamics,the vertical coupling dynamic model of vehicle and FST isolated by TVMD is established,and the vibration equations of coupled system were deduced.In addition,this thesis introduces the design method of adding TVMD system to the steel spring vibration isolator of the FST structure,and selects the indexes used to evaluate the driving safety and the vibration damping performance of the FST.Secondly,the dynamic response characteristics of FST supported by TVMD system are simulated and analyzed by using MATLAB software.Then,the applicability and effectiveness of the TVMD system to the vibration isolation of FST are discussed from two aspects of driving safety and track vibration isolation performance,and the influence of different parameters in the vibration isolator on its low frequency vibration isolation performance is analyzed.The results show that compared with the traditional steel spring FST,the TVMD system can maintain the good vibration isolation performance in the middle and high frequency bands,while the vertical vibration in the low frequency band is obviously controlled,and the vibration amplification behavior of the original steel spring FST near the natural frequency is effectively alleviated.By adjusting the stiffness,damping and inertia amplification coefficient of the steel spring system and TVMD system in the vibration isolator,the displacement peak of FST can be reduced,the vibration amplification at the natural frequency of the floating plate can be suppressed,and the low frequency isolation of the vibration isolator can be improved.However,if the parameter value is too large,the vertical acceleration peak of the supporting layer will be greatly enlarged,and the vibration control effect of FST in the low frequency section will be deteriorated.Finally,this thesis takes the acceleration vibration level of the supporting layer as the optimization goal,uses genetic algorithm to optimize the design of the parameters of the steel spring system and the TVMD system in the vibration isolator,and evaluates the low frequency vibration isolation performance of the optimized FST structure.The results show that the FST supported by optimized TVMD has both good low frequency vibration isolation performance and small vibration displacement without affecting the safety of vehicle operation.