Abstract:

Freezing method is always used in shield tunneling to facilitate the replacement of the tail brushes. However, the freezing method has such disadvantages as high cost and long construction duration. During the boring of Weisanlu Yangtze River Crossing Tunnel in Nanjing, the tail brushes have to be replaced under high water pressure and shallow highlypermeable cover. Therefore, special segments with embedded radial grouting holes are precast in advance, the grout mixing proportion, the grouting parameters and the grouting process are optimized, and effective grouting is made. In the end, the tail brushes have been replaced successfully. Compared to the conventional freezing method, the grouting method adopted in the project has lower construction cost and shorter construction duration. The practice can provide reference for similar projects in the future.

Key words: Weisanlu Yangtze Crossing Tunnel in Nanjing, shallow cover, high water pressure, strong permeability, special segment, grouting method, tail brush replacement