Abstract

The need of the underground space for the infrastructures in urban area is increasing,and especially the demand for shallow tunnels increased drastically. It is very importantthat the shallow tunnel in the urban area should fulfill not only its own safetyconditions but also the safety condition for the adjacent structures and the surroundingsub-structure. Most of the studies on the behavior of shallow tunnels concentrated onlyon their behaviors due to the local deformation of the tunnel, such as tunnel crown ortunnel sidewall. However, few studies have been performed for the behavior of theshallow tunnel due to the deformation of the entire tunnel. Therefore, in this study the behavior of the surrounding ground and the stability causedby deformation of the whole tunnel were studied. For that purpose, model tests wereperformed for the various ground surface slopes and the cover depth of the tunnel. Themodel tunnel (width 300 mm, height 200 mm) could be simulationally deformed in thevertical and horizontal direction. The model ground was built by using carbon rods ofthree types (4 mm, 6 mm, 8 mm), in various surface slopes and cover depth of thetunnel. The subsidence of ground surface, the load on the tunnel crown and thesidewall, and the transferred load near tunnel were measured. As results, the ground surface subsided above the tunnel, and its amount decreased asthe distance from the tunnel increased. The influence of a tunnel ceased in a certaindistance from the tunnel. At the inclined ground surface, the wider subsidence hasbeen occurred. The loads on the crown and the sidewall were clearly visible, but therewas no effect of the surface slope at a certain depth. The load transfer on the adjacentground was larger when the cover depth (on the horizontal surface) was lager. Thehigher the level (on the inclined surface), the wider and smaller it appeared. On the shallow tunnel under inclined surface, the transfer of the ambient load on the tunnel sidewall (low side) was clearlyvisible.