ABSTRACT
The geology, where Ritto Tunnel is located, mainly consists of discontinuous hard granite. Compared to ordinary tunnels, the tunnel cross section is very large (180m2) and the tunnel width is very wide (18m). The aim of this study is to predict and prevent the falling or sliding of rock mass or blocks along discontinuities before excavation of tunnel. In this paper, we explain the application of key block analysis on site to investigate the stability of tunnel based on the behaviors of discontinuous rock mass not only during the construction of a tunnel but also after opening to the public.
