Computational model and mechanical characteristics of linings of special-shaped shield tunnels

The change laws of rotational stiffness of ring joints with depth are analyzed based on the loading tests on three full-ring special-shaped shield linings. A computational model for shell-spring of special-shaped shield linings is established adopting the rotational stiffness of joints obtained from the prototype tests. The distribution mode of internal forces for special-shaped shield linings is determined. The test results obtained from the prototype tests are compared with those from the modified routine method and the shell-spring model. It is shown that the modified routine method as the common design method is effectively reliable, and the shell-spring model is recommended as the most effective computational model because the obtained mechanical characteristics of special-shaped shield linings are the closest to the reality. Finally, from the economical and mechanical perspectives, the application of special-shaped tunnels under shallow overburden condition is more scientific and reasonable in comparison to either the circular or the rectangular tunnels.