A wavefield superimposing method for simulating ground-borne vibration next to trains
Train traffic causes vibrations in the soil next to the railway,disturbing the surrounding environment.Numerical simulation of the vibration is known as a very time-consuming task because of the complicated system,the large area involved,and the high frequency of the vibration.To improve the efficiency of computation and ensure a controllable frequency range of the results,we herein propose a novel procedure for modeling the wavefield by superimposing numerical basic solutions.First,the dynamic responses(i.e.,basic solutions)of the track-ground system to moving time-harmonic loads are calculated in parallel.Then taking account of the interest frequency of the ground vibration,a corresponding main frequency range is selected on the spectrum of the dynamic wheel/rail force.A series of the spectrum values are sampled within the frequency range to represent the amplitudes of harmonic components of the moving loads.Taking the amplitudes as weights and adding all the corresponding basic solutions,the wavefield excited by a single wheelset is obtained.Finally,considering the influence of the axle distances and the speed of the train,the single wheelset wavefields with different lags of time and location are further superimposed to generate the total wavefield excited by the whole train.An example was computed and the results showed that the vibrations obtained are very close to the observational test data.Compared with traditional methods,the proposed procedure has high computational efficiency and desirable convenience to control the ground vibration frequency on demand,and therefore quickly realize the three-dimensional wavefield simulation of the frequency band of interest.
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