Coupled FEM-DEM analysis of mountain tunnels subjected to internal explosion and explosion induced landslide

In the present study, the onset of a landslide induced by an explosion within a shallow-buried mountain transit tunnel was simulated using a coupled FEM-DEM method. Two cases of mountain tunnel were considered for the investigation: continuous tunnel passing through the mountain body and terminal end of the tunnel. The effect of location of explosion inside the tunnel and the angle of slope on the dynamic response of the tunnel and landslide mechanism was investigated. The initiation of landslide and the location of mobilisation of overlaying soil varied as the location of explosion was changed. Time of initiation increased when the explosive was position away from the mouth of the tunnel. Change in the location of explosive also affected the response of the tunnel. Highest displacement and acceleration were observed at the crown in the tunnel section where the explosive was positioned. However, regardless of the location of explosive, substantially high displacement and acceleration were still observed at the mouth of the tunnel. Early triggering of landslide happened when the slope angle was increased for the same location of explosion. However, the effect of slope angle on the response of tunnel was minimal.