Dynamic Analysis of Open-Cut Tunnels Under Rockfall Impact

Open-cut tunnel is a typical protective structure constructed at the tunnel portal against rockfall and landslide disasters. The protective structure at the Jiefangcun Tunnel portal was taken as an engineering background. In this paper, the dynamic responses of the open-cut tunnel structure under different rockfall impacts were discussed based on numerical simulations. A series of impact simulations were conducted and the mass and impact position of the falling block was varied to clarify the effect of these factors on maximum impact force (Fm\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$F_{m}$$\end{document}) and deformation of the open-cut tunnel structure. Conclusions regarding the dynamic response of open-cut tunnel under rockfall impact were developed based on the analysis of numerical results. We conclude that under different impact energy the stress concentration phenomenon always occurs at the vault of the open-cut tunnel structure, which is easy to cause the dome to be broken. At the same time, when the falling block vertically impacts the vault, the displacement of the vault is the largest, and the displacement of the arch foot is the largest when the falling block vertically impacts the spandrel.