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

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