Abstract:

The exit section of Heishan tunnel on LanzhouChongqing railway runs in wet subsidence loess and beneath residential area with shallow cover. Advance reinforcement by mediumdiameter pipe roof and smalldiameter pipes, excavation by double side drift method, reinforcement by closelyspaced steel ribs, monitoring and reinforcement parameters adjustment, as well as assistant primary reinforcement such as cooperated arch and castinsitu C45 concrete and arch foot anchoring pipes, are executed. In the end, the tunnel passes underneath the residential area successfully.

Key words: tunnel in wet subsidence loess, shallow cover, tunneling underneath residential area, medium diameter pipe roof, advance reinforcement by small diameter pipes