Numerical study of the depth and cross-sectional shape of tunnel under surface explosion

• The difference in peak pressures in numerical and analytical methods is calculated.
• The maximum residual deformation happened at the wall center.
• The vertical PPV of the roof corner element is 47.2% of that at roof center.
• The distances 0–2 m are more vulnerable compared to the distances 2–25 m.
• The circular and horseshoe tunnels are less resistant to demolition than box shape.

Recently, blasting loads have come into consideration because of the large number of intentional or unintentional events that affected important structures around the world, obviously indicating that the topic is relevant for purposes of structural design and reliability analysis. This paper has evaluated the dynamic responses of buried tunnel in depths of 3.5, 7, 10.5 and 14 m for surface detonation of 1000 kg TNT charge in a surrounding sandy soil. The Kobe box shape subway tunnel was used as an example to evaluate and compare with semi ellipse, circular and horseshoe shape tunnel. The finite element software LS-DYNA has been used to model and to analyze the outcome of this project, specifically to be modeled in the area of the second interaction due to explosion. The results indicate that the circular and horseshoe tunnels are less resistant to demolition than the box shape tunnel however the semi ellipse tunnel is more resistant than the box shape tunnel.