Abstract: In order to analyze the vertical bearing capacity of grille arch frame structures with different cross-section shapes, 4 different types of tunnel grid arch frame models are designed, processed, loaded and analyzed. Meanwhile, the finite element software ANSYS is used to analyze the deformation ability of the model and the influence of side length and thickness of cross-section on the stability of arch frame. The study results show that: (1) The double-arch form has better mechanical properties than the single arch form, and the outer column shares 50% more load than the inner one. (2) By selecting the model with side length of 18 mm and thickness of 4 mm, the material performance can be fully used and the cost of the project can be reduced. (3) The stress concentration is easy to occur at the bending point of the arch frame, which would easily lead to damage of sprayed concrete, hence, measures such as monitoring strengthening, round arch frame connection node reduction should be adopted.

Key words: tunnel, grid arch frame, model design, cross-section shape, bearing capacity, ANSYS finite element simulation