Influence of tunnel cross-sectional shape on surface pressure change induced by passing metro trains

Abstract

Transient pressure changes induced by trains passing through tunnels have a significant influence on the structural safety of tunnels. A verified numerical method was employed in this study to explore the influence of the tunnel cross-sectional shapes with the same blockage ratio on the change in surface pressure of the tunnel. The results show that the difference mainly appears in the region affected by friction as the train enters the tunnel. The longer the cross-sectional perimeter, the larger is the positive pressure peak value. The tunnel shape has a greater influence on the negative pressure peak value, which is directly related to the distance between the train surface and the tunnel inner face. Considering the magnitude of the pressure change on the tunnel surface, a circular (C-type) tunnel with a smaller cross-sectional perimeter and aspect ratio close to 1 is better than the rectangular (R-type) and horseshoe (H-type) tunnels, which is recommended for engineering applications.