Dynamic Response Analysis of the Impact of a Rockfall on a Cantilever Shed Tunnel

Rockfalls are serious hazards in mountainous areas, and cantilever shed tunnels are a key measure against the impact of rolling stones. While in practical engineering it is very common for cantilever shed tunnels to be damaged by falling rock, few studies on the properties of the cantilever shed tunnel against the impact of falling rock have been conducted so far. In this paper, using ANSYS/LS-DYNA finite-element analysis software, a model of the common cantilever shed tunnel found in mountainous areas was established and a simulated analysis of the dynamic response process of the cantilever shed tunnel against the impact of falling rock was carried out to study the resulting deformation properties. The study results show that: 1) under the impact of falling rock, shock waves are generated in the shed tunnel and the transmission of these waves will result in stress and deforming vibrations; 2) the amount of time to reach the maximum stress at different parts of the shed tunnel is different; 3) the most dangerous places in the cantilever shed tunnel during a rockfall are the junction of the inside top wall and the plate as well as the lower part of wall, so that local strengthening should be adopted in these areas to ensure the safety of the structure; and 4) larger residual stress will remain inside the shed tunnel after the impact of the falling rock, so clearing of the fallen rock at the top of the tunnel should be undertaken in a timely manner.