Abstract:

The ground frost heave control technology used in Gongbei Tunnel on Zhuhai Connetcting Line of Hong KongZhuhaiMacao Bridge constructed by pipe roof and ground freezing method is analyzed. And then the soil temperature and ground surface displacement are predicted by finite element simulation based on thermalmechanical coupling theory; the control effects of the frost heave by using pregrouting around pipe curtain and frozen depth limiting tubes are compared and analyzed. The results show that: (1) The permeability, frost heave rate and water transfer of the ground are reduced by pregrouting around pipe curtain, which plays a critical role in the frost heave control. (2) The frozen depth limiting tubes can relieve the development rate of the frozen soil, strengthen the effect of frost heave control, and as well, serve as an effective supplementary of the frost heave control. The comparison between simulated ground surface displacement and the field monitoring results is made; and the frost heave control principle is explained from the aspects of distribution of ground temperature and ground surface displacement. The results can provide technical support for successful construction of Gongbei Tunnel, improve the construction technique of the superlarge crosssection tunnel under complex conditions in China, and provide valuable reference for the construction of tunnels using similar artificial ground freezing method in the future.

Key words: Gongbei Tunnel, pipe roof and ground freezing method, thermalmechanical coupling, artificial ground freezing, grouting, depth limiting tube, frost heave control