Tunnel construction in China is increasing year by year. With the passage of time, China will usher in the peak period of tunnel engineering repair, and it is vital to study in advance the influential nature of tunnel lining crack disease as well as management measures. By summarising a large amount of relevant literature, this paper analyses the main locations where cracks are generated in tunnel linings. Through the method of finite element numerical analysis, 24 cases of cracks of different widths and depths were modelled and calculated for each location of lining vaults, shoulders and side walls, respectively, to analyse the influence of different cases on the internal forces and deformation of the lining. The study shows that the stress concentration around the crack tip decreases with the increase of the crack width, while the stress concentration around the crack tip increases with the increase of the crack depth. The stresses in the other main parts of the lining increase after the crack is created, which has a deteriorating effect on the load-bearing capacity and stability of the lining structure. With the increase in crack width and depth, the sinking deformation of the vault and the heaving deformation of the back arch increase, especially when the cracks are large, but lining cracking has less effect on the lateral deformation of the lining. Compared to cracks in the top and shoulder of the arch, cracks in the side walls have a more pronounced effect on the distribution of internal forces around the cracks.

In engineering practice, longitudinal brace systems for column-braced systems are designed to resist both horizontal and vertical loads. In previous experimental research on horizontal brace forces for column-braced systems of intermediate height, only vertical loads were considered. Hence, this paper presents a numerical simulation of numerous column-braced systems subjected to horizontal and vertical loads. In the numerical simulation, second-order analysis was adopted, and the Monte Carlo method was used to incorporate the randomness of initial imperfections in the horizontal brace and column. From the finite element (FE) analyses and probability model statistics, the normal probability density equation for intermediate-height horizontal brace forces under horizontal and vertical loads was obtained, and the corresponding design intermediate-height horizontal brace forces were determined and compared with those under vertical loads only. The results indicate that the design intermediate-height horizontal brace forces under horizontal and vertical loads are significantly greater than those under only vertical loads, and that the design intermediate-height horizontal brace forces under horizontal and vertical loads are also greater than the simple superposition results of horizontal loads and intermediate-height horizontal brace forces under only vertical loads.