Abstract:

 Due to the presence of karsts, Nanling tunnel is one of the difficult tunnels even during the construction stage. Soon after the completion of the tunnel, the treatment of the defects of the tunnel begins. Due to the shallow cover of the tunnel, the close circulations between the ground water and surface water and the busy traffics of the BeiingGuangzhou railway, the defects of the tunnel can not be completely eliminated in the several treatment campaigns. The article introduces the geological conditions, design and construction, present situation of the defects and the defect treatment measures of Nanling tunnel. The article also provides some recommendations on the alignment determination of other tunnels in the future.

Key words:  tunnel, karst, defect  treatment