Abstract: Using the liquid nitrogen freezing technique in the shielded excavation in the tunnel engineering has become increasingly mature. The project case histories of applying the liquid nitrogen freezing method in the shielded tunnel excavation are summarized in this paper and the differences between the liquid nitrogen freezing method and the traditional seepage prevention improvement methods in the shielded excavation are also summarized. The statistical results on the completed projects inside China indicate that the application of liquid nitrogen freezing methods were concentrated at access portals and the maintenance and replacement of tail brushes. Compared with the traditional method, the liquid nitrogen freezing method has its own advantages.

Key words: Liquid Nitrogen Freezing, Shielded Excavation, Access Portal, Tail Brush