关键词: 盾构, 无主体结构, 接收技术, 整体平移, 地铁车站, 工期滞后

Abstract:  The shield cannot be received results from delayed construction of metro station main structure. Therefore, a case study is conducted on the Dashadong station of Guangzhou metro line 7, and the shield receiving technology in superdeep foundation pit without main structure is proposed. First, the foundation pit is excavated to the design elevation and the construction of the main structure of the end well is suspended. Second, measures such as adjusting the support position of receiving well, installing sealing device of underground diaphragm wall tunnel door, and fixing receiving bracket are taken under the condition of only enclosure structure and floor cushion. Finally, by continuously monitoring the deformation and displacement of the underground diaphragm wall at the end well, the entire process of risk monitoring and early warning can be realized to ensure smooth shield receive, translate and lift out. Field application results show the following: (1) The steel reinforcement, concrete, stone excavation, and steel ring were reduced by 142 t, 644 m3, 1 680 m3, and 2, respectively, and the construction period was shortened by 160 days. (2) The maximum deformation at the end well of Dashadong station is 21.2 mm, which is less than the warning value of 24 mm required in the specification. The maximum deformation rate is 1.5 mm/d, which is less than the warning value of 2.4 mm/d required in the specification. The technology recommended can ensure safe shield receiving in ultradeep foundation pit, guarantee the construction period, avoid shield head felling, air leakage at the shield tail, and jamming caused by a long time of shutdown.

Key words: shield, foundation pit without main structure; receiving technology, monolithic movement, metro station, construction period delay