The structure of the tunnel exit and entrance (Portal) will be the main issues to consider as well as the design of the tunnel due to the entrance and exit of the tunnel is covered above tunnel (Covering Depth), which is a little hard rock or soil where it will remain active. In addition, usually the entrance and exit of the tunnel are located in areas where there are poor-quality stones, which may cause erosion of the slope (Slope Failure or Landslide) to fallen rock (Rock Fall) in the area. The entrance and exit of the tunnel can be defined from a distance covered over the tunnel is approximately 1 to 2 times the diameter of the tunnel, as shown in Figure 5.12-2 so on entrance and exit structure of the tunnel needs to be analyzed and designed to prevent erosion, suitable geological conditions. The format and dimensions of the tunnel
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