Understanding the dynamic response characteristics of subway segment and sur-rounding soil under different track structures can provide important basis for the vibration re-duction technology of subway track structure.Large-scale physical model tests were conducted,and three different subway tunnel models were designed:pure segment without ballast bed,regular ballast bed,and rubber floating plate ballast bed.Based on the actual sub-way train vibration signal and the analysis method of Fourier transform time-frequency domain,the logarithm of peak acceleration and frequency response function were used as evalu-ation indicators to analyze the dynamic response change rules of different tunnel segment struc-tures and surrounding soil.The research results show that the dynamic response change of the train load frequency domain is divided into three stages.In stage 1(0-20 Hz),the frequency response function of the track structure is negatively correlated with the load frequency.In stage Ⅱ(20-150 Hz),the dynamic response increases with the change of load frequency,with local fluctuations.Vibration amplification occurs at the peak of 50 Hz and 110 Hz,respec-tively.In stage Ⅲ(150-250 Hz),the dynamic response is positively correlated with the load frequency.The regular ballast bed and rubber floating plate ballast bed have a good vibration reduction effect in the frequency range of 50-250 Hz,but have less attenuation effect on low-frequency vibration.The dynamic response of the three track structure segments at different positions on the ring decreases with the increase of distance from the vibration source.The ex-istence of the ballast bed structure reduces the amplitude of attenuation of vibrational wave propagation at the same circle test point.The dynamic response between rings shows a gradu-ally decreasing trend with the increase of distance from the vibration source.The existence of the ballast bed structure and rubber floating plate structure changes the frequency response characteristics of the surrounding soil layer,and vibration amplification occurs in the high-fre-quency range,but the overall dynamic response is smaller than that of the pure segment with-out a ballast bed structure around the soil layer.The dynamic response in the soil layer gradu-ally decreases with the increase of distance from the vibration source,and the attenuation am-plitude of the dynamic response from arch to arch crown is 20.3％.
model teststunnel structurespower responsefrequency response functiontime-frequency analysis
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