Numerical study on space-time distribution characteristics of pressure waves generated by a high-speed metro train operating along various lines of bifurcated tunnels

Journal article, 2024

Bifurcated tunnels have many lines that significantly improve the utilization of underground space. However, the pressure waves (PWs) generated by a metro train in a tunnel may cause irreversible damage to the tunnel, particularly the more complex wave system generated by a train in a variable cross section bifurcated tunnel. Overset grid technology was adopted to simulate trains operating in tunnels; the differences between train operation in single-line and bifurcated tunnels were analyzed, and the PW characteristics of trains operating on three different lines in a bifurcated tunnel were compared. The numerical method was verified experimentally, and the pressure change trend fitted well. The results show the following: The bifurcated tunnel will increase the train surface PWs. The maximum pressure (pmax) of the surface of the train is reduced by more than 60% on average, and the minimum pressure (pmin) is basically the same. The peak-to-peak pressure (Δp) increases by more than 50% on average, but the distribution trend does not change. The influence of the bifurcated tunnel on the tunnel wall pmax, pmin, and Δp is bounded by the bifurcation area. The difference in surface pressure of trains operating on different lines in the bifurcated tunnel is mainly caused by the bifurcated area. The distribution trend of the pmax, pmin, and Δp of trains operating on different lines is the same. However, the pmax, pmin, and Δp of the wall of the train operating line are greater than those of the non-operating line. These findings can provide a reference for the design of bifurcated tunnels and route planning of metro trains.