Measurment And Numerical Simulation Of Environmental Vibration Caused By Tram

With the rapid development of urbanization,the urban population is becoming more and more dense,and the traffic pressure is increasing sharply.The new rail transit system,which is a new type of rail transit system to alleviate traffic congestion,has developed rapidly in China in recent years.When the train is running,the vibration of the surrounding ground and buildings will have a negative impact on people’s production and life,as well as the use of ancient buildings and precision instruments.The environmental vibration caused by rail transit is receiving more and more attention.In this paper,the environmental vibration caused by trams is studied.The 202 trams in Dalian are used as research objects to conduct on-site vibration data acquisition and test.The system analyzes the environmental vibration propagation law caused by trams and evaluates influences of the environmental vibration.At the same time,the environmental vibration prediction model of 2D and 3D trams is established,and the ground vibration response caused by the operation of the tram is calculated and compared with the measured results to verify the correctness of the numerical model.The main research contents are as follows:(1)The on-site vibration acceleration measurement was carried out on the section of the 202-way tram Xinghai Square in Dalian City,and the vibration acceleration data at each measurement point was obtained.The measured vibration acceleration data was Fourier transformed to obtain 1/3 times The distribution over the frequency range,and then the calculation of the environmental evaluation standard vibration level.By analyzing the distribution of vibration acceleration in the time domain and frequency domain,the variation of environmental vibration with distance and train running speed caused by tram is obtained and its distribution in the frequency domain.(2)Using the finite element software to establish a two-dimensional orbit-soil model,and simultaneously establish a simplified model of the two-dimensional tram and calculate the orbital reaction force to load it into the two-dimensional model to simulate the vibration response of the tram under running condition.The results of the numerical simulation were respectively analyzed in the time domain and the frequency domain.(3)Perform the hammer stroke test in the test section,and at the same time obtain the vibration acceleration response generated at each measuring point on the surrounding soil surface under the action of the striking force.A three-dimensional orbit-soil model is established.Based on the actual soil layer stratification,an orthogonal test table is established taking the elastic modulus of the soil layer in the experimental area as a consideration to simulate the vibration acceleration response generated by the impact force of the experiment.The numerical simulation data of orthogonal experiment is used as a sample of neural network parameter inversion,and the inversion of soil parameters is used to obtain a set of elastic moduli consistent with the results of the hammer test.(4)Using the multi-body dynamics software to establish the tram model,the wheel-rail force time-history curve was generated when the tram is running in consideration of the track irregularity can be numerically calculated as the train vibration load excitation.The numerical analysis of the three-dimensional model is carried out,and a set of elastic modulus of the inversion is used as the soil layer parameter,and the calculated wheel-rail force is loaded into the three-dimensional model to simulate the vibration response of the tram under running condition.The numerical simulation results and field test results are compared in the time domain and the frequency domain to verify the correctness of the prediction model.