Sub-rectangular Tunnel Behaviour under Static Loading

Circular- and rectangular-shaped tunnels are usually utilized when excavating at shallow depths in urban areas. Nevertheless, special-shaped tunnels such as subrectangular tunnels were recently considered to be used for overcoming some drawbacks of circular and rectangular tunnels in terms of low utilization space ratio and stress concentration at the corners, respectively. Using numerical analyses, this paper focuses on indicating the different behaviour of sub-rectangular tunnels under static loading in comparison with circular and rectangular ones having the same utilization space. It allows designers to decide the appropriate tunnel shape solution that should be used. The influence of parameters, including soil deformability, lateral earth pressure coefficient, and lining thickness, on the behaviour of different tunnel shapes under static loadings is also investigated. The results indicated a significant difference in the behaviour of sub-rectangular tunnels in comparison with the circular and rectangular ones when considering no-slip and full-slip conditions for the soil-lining interaction.

Automated summary

This paper focuses on the different behavior of sub-rectangular tunnels under static loading compared to circular and rectangular tunnels. It provides designers with information to choose the appropriate tunnel shape solution and investigates the influence of various parameters on tunnel behavior.