Abstract:

Tunneling in karst area shows the situation of complex geological condition, great construction difficulty and high risk. In order to overcome the influence of karst on tunneling, many treatment measures are applied. The application of arch bridge in tunneling in karst areas is presented in respect of concept, design key points and construction key points. At the same time, the treatment of the karst in No.2 Changyingba tunnel is given in this paper. Back filling and arch bridge are used to treat the karst in this tunnel. This provides certain experiences for karst tunnel construction. Finally, the overall analysis shows that the arch bridge option, which is suitable for tunneling across large dry karst cavities, is a good karst treatment method. During the application of arch bridges, the karsts, surrounding rock mass, hydrology, surrounding environment, construction cost, construction risk and structural safety should be taken into account.

Key words: tunnel construction, karst tunnel, dry karst cavity, span arch