Numerical Analysis to Examine the Effect of Landslides on Tunnels

In the vicinity of known landslide zones, tunnel routes should be designed such that the distance between the landslide and the tunnel is sufficient to avoid adverse impact of the landslide on the tunnel. This requires a good understanding of the effects of the landslide on the tunnel. We modeled the ground surrounding the tunnel and the landslide using numerical analysis to evaluate the quantitative effect of the tunnel offset from the landslide on ground stresses and displacement of the ground surface and tunnel crown. We considered the effects under different ground conditions and examined two different cases, when the landslide occurs before tunnel construction and where the landslide movement occurs after tunnel construction. We found that the required offset distance between the landslide and the tunnel depended on whether the landslide occurred before or after tunnel excavation and the characteristics of the site conditions, and the method of setting the offset distance needs to consider the conditions at each site. As a result, we conclude that under some conditions, the offset required by current technical standards may be inadequate and further investigation would be required