Vibration Transmission Characteristic Analysis of the Metro Turnout Area by Constant-Q Nonstationary Gabor Transform

The problem of vibration in turnout zones caused by passing trains has become increasingly serious due to the complexity of the structure and force of metro turnouts. However, there are only a few studies focusing on the vibration transmission characteristics in turnout zones. In this paper, three typical turnouts in a city were studied to test the vibration responses of track slabs and a tunnel wall in the switch zone and the crossing zone when a train was passing a turnout. First, the short-time Fourier transform, wavelet transform, and constant-Q nonstationary Gabor transform (CQ-NSGT) were applied to the typical time-domain signal of tunnel wall respectively. The comparison results showed that CQ-NSGT delivered a higher time resolution and a higher frequency resolution. Based on this, the CQ-NSGT was used to analyze the vibration signal of the track slabs and specifically study the vertical vibration characteristics of the track slabs in the turnout zone toward the tunnel at the time when a train was passing. The result showed the vibration signal transmitted to the tunnel wall from the track slabs in both the switch and crossing zones will experience high-frequency vibration attenuation. It was noted that different train types have no effects on the vibration signal transmission rule, but an increase in the train speed will increase the vibration energy and expand the frequency band when the signal was transmitted to the tunnel wall.