| With the rapid development of urbanization in our country, constructions of tunnels crossing river or sea are booming. Recent years, the super-large-crossing-river tunnels which are under construction have nearly all encountered such problems as complex geological conditions, shallow-buried, high water pressure, long-distance driving and so on, which put forward a huge challenge to tunnel builders. Based on Nanjing Yangtze tunnel engineering, this paper has discussed the application of super-large slurry shield construction and waterproof technology. The main content of this paper have listed as followings:1. Based on the collection of super-large-crossing-river tunnels at home and abroad, the super-large slurry shield construction and waterproof technology have been summarized.2. Shield launching technology adopted in Nanjing Yangtze tunnel has been introduced. Freezing soil wall combined with high pressure jet grouting pile of full range of reinforcement have been used to consolidate the soil. Before formal tunnelling, attempt tunnelling is carried out. With the process of it, workers should be familiar with segment assembly operation and driving method, collect driving data and gather experience for the next long-distance driving.3. Segments selection and assembly technology of Nanjing Yangtze tunnel has been introduced. Based on segment type, leading quantity, shield tail gap, jack journey and construction difficulty, German VMT system has been used to select the right segment type which is suit for this project, and then refine control measurements have been made to make sure of the assembly accuracy of segments.4. Considering of the jack thrust, advancing rate, rotating speed and torque of cutter, shield attitude control and synchronous grouting, super-large long-distance shield driving parameters control technology have been proposed, and then based on Nanjing Yangtze tunnel, construction risk analysis has been made, with relative prevention and control measures.5. High precision steel mould quality control and segment double seal waterproof technology have been summarized in Nanjing Yangtze tunnel. The attached vibrators combined with heavy duty structure have been adopted in the steel mould, which have improved the mould quality-control accuracy and labor efficiency. Waterproof seal have been adopted inside and outside the segment joint. At the outside, the porous elastic rubber, combined with EPDM and WSR, have been used, at the inside, polyether urethane WSR seal have been used. |
