Study on aerodynamic pressures caused by double-train tracking operation in a metro tunnel

Abstract

The continuous construction of extra-long metro tunnels and the shortened departure intervals enable double trains to simultaneously drive in the same tunnel direction to be possible. Transient pressure changes induced by trains passing through tunnels have a remarkable influence on the structural safety of tunnels. In this study, pressure waves generated by single and double trains passing through the tunnel are both explored by numerical simulation. The accuracy and feasibility of the simulation method of double train tracking operation is verified by comparison with the small-scale experimental research. Based on the verified simulation method, the pressure wave and its propagation characteristics in the aforementioned two situations are investigated. Variation of transient pressure on the surface of the train and tunnel are compared and analyzed. Results show no obvious difference on the generation and propagation mechanism of pressure waves between the two typical situations. However, the propagation of the pressure wave is found to be more complicated in the double train tracking mode. More concretely, in the double train tracking mode, the maximum transient pressure P-max, minimum transient pressure P-min, and the peak-to-peak value of transient pressure ΔP on the first train surface are observed to be same as those in the single train condition, whereas those of the second train denote different values. The transient pressure at different positions in the tunnel and the waveform after the second train entering the tunnel are different compared to that in the single train condition, while the peak value exhibits insignificant difference. Moreover, the maximum pressure, minimum pressure, and maximum peak-to-peak pressure occur inside tunnel denote no obvious difference in the two typical scenarios.