Study On Modeling Method Of Rail Transit Damping Track Based On Viscoelastic Theory

At present,many cities in China vigorously develop rail transit to alleviate urban traffic congestion,but also caused environmental vibration problems can not be ignored.Therefore,the rail transit construction department has invested a lot of money to take vibration reduction measures,and many people in the industry have begun to study new materials and vibration reduction tracks.Whether the existing damping measures or the new damping measures in the research and development stage,the accurate analysis of the damping effect can provide an important basis for the damping design.At present,the commonly used method is the numerical simulation method,so it is particularly important to accurately simulate the damping products by using the appropriate constitutive model.For the two special materials of damping pad and rubber concrete,this paper conducts in-depth research on the modeling method,and proposes five new damping methods to predict the damping effect.The main research work and results are as follows :(1)The application range of four classical viscoelastic constitutive models(Maxwell model,Kelvin model,three-parameter model and Burgers model)was analyzed.Two constitutive models suitable for damping pad and rubber concrete material were preliminarily selected.The Jacobian matrix of the constitutive equation was deduced,and the ABAQUS subroutine was written to make these two constitutive models realize in ABAQUS finite element software.(2)In order to study the dynamic characteristics of damping pad materials,the vibration test of damping pad floating slab track was carried out in the underground laboratory of Beijing Jiaotong University.According to the actual situation of the test site,the three-dimensional dynamic analysis model of the track-tunnel-soil layer was established.The elastic body,spring-damping element and three-parameter model were used to simulate the damping pad,respectively.The calculated values were compared with the measured values.The results show that the three-parameter viscoelastic modeling method can more accurately simulate the dynamic characteristics of the damping pad.(3)In order to study the dynamic characteristics of rubber concrete damping track bed,a 1:1 automatic drop hammer model test of rubber concrete damping track bed and ordinary concrete track bed was carried out on the test platform of Beijing Jiaotong University.The three-dimensional dynamic analysis model of track bed-cap-soil is established according to the test site conditions.The elastic constitutive model(Rayleigh damping)and Kelvin viscoelastic constitutive model are used to simulate the dynamic response of rubber concrete,respectively.The results show that the Kelvin viscoelastic modeling method can simulate the dynamic characteristics of rubber concrete more accurately.(4)Five new damping measures are envisaged.The three-parameter viscoelastic constitutive model proposed in the above study is used to simulate the damping pad and the Kelvin viscoelastic constitutive model is used to simulate the rubber concrete damping track bed.Combined with the actual engineering background,the actual damping effects of the five new types of damping tracks are predicted and analyzed.