| 摘要 |
A protective shelter such as a bomb shelter can be entered into or left through an elongate tunnel connected with an enclosed shelter area and including at least two spaced apart angle sections formed by correspondingly curved side walls of the tunnel. The curved tunnel sections serve to prevent the build-up of a destructive pressure head in the tunnel. The walls of the tunnels are constructed of prefabricated concrete blocks joined in situ by suitable screw connections. |
